Comma showing up in front of Titles in results

That's curious. Are you using the Solr backend, or the "Highlighting" processor (or both)?
Does this always occur when the filter (the search field) is present, or only when you input something there?
What are the view's style settings? Unordered list of Fields?
Do you have some additional modules (custom or contrib) installed that could influence this behavior (i.e., modules integrating with Views or Search API – particularly less popular ones). I'm pretty sure that this problem doesn't exist in most installations, so there's got to be something specific about your setup.
From which version did you update, 1.18?
If you are a bit tech-savvy, the optimum would be if you could do a git bissect to see which change in particular introduced the problem.

PS: It seems you (like many others – it's really easy to misinterpret) are confused by the "Issue tags" field. As the guidelines state, they aren't meant for free text tags related to the issue, but only for specific categorization purposes, usually by module maintainers.
So, if you aren't sure your current usage is correct, please just leave the field empty.

For what is is worth after making some various config changes to a previously working search API view, this started happening us also. An comma appears before every result title, and if you view source you find that there is an empty href in there pointing to the node:

<a href="node/1"></a>, <a href="node/1>My node</a>

I was able to fix by excluding the TITLE field from the excerpt settings within the Highlight processor...

Are you maybe using a Solr backend and have incompatible processors enabled on your Search API index? (Most of them shouldn't be used along with Solr.)

I'm having this same issue. I'm using the search database module, not Solr or anything else. I do have the highlighting turned on.

It only occurs when using the fields that have the index name in the front, like "[Index Name]: [field] (indexed)", not the ones that start with Search:, like "Search: [Index Name] results"

Excluding the title / file name in the highlighting processor does seem to fix it, but I do want the word highlighted in there...

Here's my view's settings:
Format: HTML List
Show: Fields

Fields
Node Index: Title (indexed)
File Index: File name (indexed)
Search: Excerpt

Filter Criteria
Search: Fulltext search (exposed)
Node Index: Content type (indexed) (exposed)
File Index: File type (indexed) (exposed)

Sort Criteria
Search: Relevance (desc)

Here's the Export code for the view (I'm using the Page display):

$view = new view();
$view->name = 'intranet_search';
$view->description = '';
$view->tag = 'default';
$view->base_table = 'search_api_multi';
$view->human_name = 'Search';
$view->core = 7;
$view->api_version = '3.0';
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */

/* Display: Master */
$handler = $view->new_display('default', 'Master', 'default');
$handler->display->display_options['title'] = 'Search';
$handler->display->display_options['use_ajax'] = TRUE;
$handler->display->display_options['use_more_always'] = FALSE;
$handler->display->display_options['access']['type'] = 'none';
$handler->display->display_options['cache']['type'] = 'none';
$handler->display->display_options['query']['type'] = 'views_query';
$handler->display->display_options['exposed_form']['type'] = 'basic';
$handler->display->display_options['pager']['type'] = 'full';
$handler->display->display_options['pager']['options']['items_per_page'] = '20';
$handler->display->display_options['pager']['options']['offset'] = '0';
$handler->display->display_options['pager']['options']['id'] = '0';
$handler->display->display_options['pager']['options']['quantity'] = '9';
$handler->display->display_options['style_plugin'] = 'list';
$handler->display->display_options['style_options']['default_row_class'] = FALSE;
$handler->display->display_options['style_options']['row_class_special'] = FALSE;
$handler->display->display_options['style_options']['wrapper_class'] = '';
$handler->display->display_options['row_plugin'] = 'search_api_multi';
$handler->display->display_options['row_options']['view_mode'] = array(
  'node' => 'search_result',
  'file' => 'search_result',
);
/* No results behavior: Global: Text area */
$handler->display->display_options['empty']['area']['id'] = 'area';
$handler->display->display_options['empty']['area']['table'] = 'views';
$handler->display->display_options['empty']['area']['field'] = 'area';
$handler->display->display_options['empty']['area']['label'] = 'No Results Found.';
$handler->display->display_options['empty']['area']['empty'] = TRUE;
$handler->display->display_options['empty']['area']['content'] = 'We\'re sorry, we couldn\'t find any results for your search.';
$handler->display->display_options['empty']['area']['format'] = 'full_html';
/* Field: Search: Node Index results */
$handler->display->display_options['fields']['node_index']['id'] = 'node_index';
$handler->display->display_options['fields']['node_index']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['node_index']['field'] = 'node_index';
$handler->display->display_options['fields']['node_index']['label'] = '';
$handler->display->display_options['fields']['node_index']['element_type'] = 'h2';
$handler->display->display_options['fields']['node_index']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['node_index']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['node_index']['link_to_entity'] = 1;
$handler->display->display_options['fields']['node_index']['view_mode'] = 'full';
$handler->display->display_options['fields']['node_index']['bypass_access'] = 0;
/* Field: Search: File Index results */
$handler->display->display_options['fields']['file_index']['id'] = 'file_index';
$handler->display->display_options['fields']['file_index']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['file_index']['field'] = 'file_index';
$handler->display->display_options['fields']['file_index']['label'] = '';
$handler->display->display_options['fields']['file_index']['element_type'] = 'h2';
$handler->display->display_options['fields']['file_index']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['file_index']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['file_index']['link_to_entity'] = 1;
$handler->display->display_options['fields']['file_index']['view_mode'] = 'teaser';
$handler->display->display_options['fields']['file_index']['bypass_access'] = 0;
/* Sort criterion: Search: Relevance */
$handler->display->display_options['sorts']['search_api_relevance']['id'] = 'search_api_relevance';
$handler->display->display_options['sorts']['search_api_relevance']['table'] = 'search_api_multi';
$handler->display->display_options['sorts']['search_api_relevance']['field'] = 'search_api_relevance';
/* Filter criterion: Search: Fulltext search */
$handler->display->display_options['filters']['search_api_multi_fulltext']['id'] = 'search_api_multi_fulltext';
$handler->display->display_options['filters']['search_api_multi_fulltext']['table'] = 'search_api_multi';
$handler->display->display_options['filters']['search_api_multi_fulltext']['field'] = 'search_api_multi_fulltext';
$handler->display->display_options['filters']['search_api_multi_fulltext']['operator'] = 'OR';
$handler->display->display_options['filters']['search_api_multi_fulltext']['group'] = 1;
$handler->display->display_options['filters']['search_api_multi_fulltext']['exposed'] = TRUE;
$handler->display->display_options['filters']['search_api_multi_fulltext']['expose']['operator_id'] = 'search_api_multi_fulltext_op';
$handler->display->display_options['filters']['search_api_multi_fulltext']['expose']['label'] = 'Keyword Search';
$handler->display->display_options['filters']['search_api_multi_fulltext']['expose']['operator'] = 'search_api_multi_fulltext_op';
$handler->display->display_options['filters']['search_api_multi_fulltext']['expose']['identifier'] = 'search_api_multi_fulltext';
$handler->display->display_options['filters']['search_api_multi_fulltext']['expose']['remember_roles'] = array(
  2 => '2',
  1 => 0,
  4 => 0,
  3 => 0,
  6 => 0,
);
/* Filter criterion: Node Index: Content type (indexed) */
$handler->display->display_options['filters']['node_index_type']['id'] = 'node_index_type';
$handler->display->display_options['filters']['node_index_type']['table'] = 'search_api_multi';
$handler->display->display_options['filters']['node_index_type']['field'] = 'node_index_type';
$handler->display->display_options['filters']['node_index_type']['value'] = array();
$handler->display->display_options['filters']['node_index_type']['group'] = 1;
$handler->display->display_options['filters']['node_index_type']['exposed'] = TRUE;
$handler->display->display_options['filters']['node_index_type']['expose']['operator_id'] = 'node_index_type_op';
$handler->display->display_options['filters']['node_index_type']['expose']['label'] = 'Filter by Content Type';
$handler->display->display_options['filters']['node_index_type']['expose']['operator'] = 'node_index_type_op';
$handler->display->display_options['filters']['node_index_type']['expose']['identifier'] = 'node_index_type';
$handler->display->display_options['filters']['node_index_type']['expose']['multiple'] = TRUE;
$handler->display->display_options['filters']['node_index_type']['expose']['remember_roles'] = array(
  2 => '2',
  1 => 0,
  4 => 0,
  3 => 0,
  6 => 0,
);
$handler->display->display_options['filters']['node_index_type']['expose']['reduce'] = 0;
/* Filter criterion: File Index: File type (indexed) */
$handler->display->display_options['filters']['file_index_type']['id'] = 'file_index_type';
$handler->display->display_options['filters']['file_index_type']['table'] = 'search_api_multi';
$handler->display->display_options['filters']['file_index_type']['field'] = 'file_index_type';
$handler->display->display_options['filters']['file_index_type']['value'] = array();
$handler->display->display_options['filters']['file_index_type']['exposed'] = TRUE;
$handler->display->display_options['filters']['file_index_type']['expose']['operator_id'] = 'file_index_type_op';
$handler->display->display_options['filters']['file_index_type']['expose']['label'] = 'Filter by File Type';
$handler->display->display_options['filters']['file_index_type']['expose']['operator'] = 'file_index_type_op';
$handler->display->display_options['filters']['file_index_type']['expose']['identifier'] = 'file_index_type';
$handler->display->display_options['filters']['file_index_type']['expose']['multiple'] = TRUE;
$handler->display->display_options['filters']['file_index_type']['expose']['remember_roles'] = array(
  2 => '2',
  1 => 0,
  4 => 0,
  3 => 0,
  6 => 0,
);
$handler->display->display_options['filters']['file_index_type']['expose']['reduce'] = 0;

/* Display: Page */
$handler = $view->new_display('page', 'Page', 'page');
$handler->display->display_options['defaults']['exposed_form'] = FALSE;
$handler->display->display_options['exposed_form']['type'] = 'better_exposed_filters';
$handler->display->display_options['exposed_form']['options']['submit_button'] = 'Search';
$handler->display->display_options['exposed_form']['options']['reset_button'] = TRUE;
$handler->display->display_options['exposed_form']['options']['bef'] = array(
  'general' => array(
    'allow_secondary' => 0,
    'secondary_label' => 'Advanced options',
    'collapsible_label' => NULL,
    'combine_rewrite' => NULL,
    'reset_label' => NULL,
    'bef_filter_description' => NULL,
    'any_label' => NULL,
    'filter_rewrite_values' => NULL,
  ),
  'search_api_multi_fulltext' => array(
    'bef_format' => 'default',
    'more_options' => array(
      'is_secondary' => 0,
      'any_label' => '',
      'bef_filter_description' => '',
      'tokens' => array(
        'available' => array(
          0 => 'global_types',
          'secondary_label' => NULL,
          'collapsible_label' => NULL,
          'combine_rewrite' => NULL,
          'reset_label' => NULL,
          'bef_filter_description' => NULL,
          'any_label' => NULL,
          'filter_rewrite_values' => NULL,
        ),
        'secondary_label' => NULL,
        'collapsible_label' => NULL,
        'combine_rewrite' => NULL,
        'reset_label' => NULL,
        'bef_filter_description' => NULL,
        'any_label' => NULL,
        'filter_rewrite_values' => NULL,
      ),
      'rewrite' => array(
        'filter_rewrite_values' => '',
        'secondary_label' => NULL,
        'collapsible_label' => NULL,
        'combine_rewrite' => NULL,
        'reset_label' => NULL,
        'bef_filter_description' => NULL,
        'any_label' => NULL,
      ),
      'secondary_label' => NULL,
      'collapsible_label' => NULL,
      'combine_rewrite' => NULL,
      'reset_label' => NULL,
      'filter_rewrite_values' => NULL,
    ),
    'secondary_label' => NULL,
    'collapsible_label' => NULL,
    'combine_rewrite' => NULL,
    'reset_label' => NULL,
    'bef_filter_description' => NULL,
    'any_label' => NULL,
    'filter_rewrite_values' => NULL,
  ),
  'node_index_type' => array(
    'bef_format' => 'bef',
    'more_options' => array(
      'bef_select_all_none' => 0,
      'bef_collapsible' => 0,
      'is_secondary' => 0,
      'any_label' => '',
      'bef_filter_description' => '',
      'tokens' => array(
        'available' => array(
          0 => 'global_types',
          'secondary_label' => NULL,
          'collapsible_label' => NULL,
          'combine_rewrite' => NULL,
          'reset_label' => NULL,
          'bef_filter_description' => NULL,
          'any_label' => NULL,
          'filter_rewrite_values' => NULL,
        ),
        'secondary_label' => NULL,
        'collapsible_label' => NULL,
        'combine_rewrite' => NULL,
        'reset_label' => NULL,
        'bef_filter_description' => NULL,
        'any_label' => NULL,
        'filter_rewrite_values' => NULL,
      ),
      'rewrite' => array(
        'filter_rewrite_values' => '',
        'secondary_label' => NULL,
        'collapsible_label' => NULL,
        'combine_rewrite' => NULL,
        'reset_label' => NULL,
        'bef_filter_description' => NULL,
        'any_label' => NULL,
      ),
      'secondary_label' => NULL,
      'collapsible_label' => NULL,
      'combine_rewrite' => NULL,
      'reset_label' => NULL,
      'filter_rewrite_values' => NULL,
    ),
    'secondary_label' => NULL,
    'collapsible_label' => NULL,
    'combine_rewrite' => NULL,
    'reset_label' => NULL,
    'bef_filter_description' => NULL,
    'any_label' => NULL,
    'filter_rewrite_values' => NULL,
  ),
  'file_index_type' => array(
    'bef_format' => 'bef',
    'more_options' => array(
      'bef_select_all_none' => 0,
      'bef_collapsible' => 0,
      'is_secondary' => 0,
      'any_label' => '',
      'bef_filter_description' => '',
      'tokens' => array(
        'available' => array(
          0 => 'global_types',
          'secondary_label' => NULL,
          'collapsible_label' => NULL,
          'combine_rewrite' => NULL,
          'reset_label' => NULL,
          'bef_filter_description' => NULL,
          'any_label' => NULL,
          'filter_rewrite_values' => NULL,
        ),
        'secondary_label' => NULL,
        'collapsible_label' => NULL,
        'combine_rewrite' => NULL,
        'reset_label' => NULL,
        'bef_filter_description' => NULL,
        'any_label' => NULL,
        'filter_rewrite_values' => NULL,
      ),
      'rewrite' => array(
        'filter_rewrite_values' => '',
        'secondary_label' => NULL,
        'collapsible_label' => NULL,
        'combine_rewrite' => NULL,
        'reset_label' => NULL,
        'bef_filter_description' => NULL,
        'any_label' => NULL,
      ),
      'secondary_label' => NULL,
      'collapsible_label' => NULL,
      'combine_rewrite' => NULL,
      'reset_label' => NULL,
      'filter_rewrite_values' => NULL,
    ),
    'secondary_label' => NULL,
    'collapsible_label' => NULL,
    'combine_rewrite' => NULL,
    'reset_label' => NULL,
    'bef_filter_description' => NULL,
    'any_label' => NULL,
    'filter_rewrite_values' => NULL,
  ),
  'secondary_label' => NULL,
  'collapsible_label' => NULL,
  'combine_rewrite' => NULL,
  'reset_label' => NULL,
  'bef_filter_description' => NULL,
  'any_label' => NULL,
  'filter_rewrite_values' => NULL,
);
$handler->display->display_options['exposed_form']['options']['input_required'] = 1;
$handler->display->display_options['exposed_form']['options']['text_input_required'] = 'Enter keywords to search for or choose from available filters.';
$handler->display->display_options['exposed_form']['options']['text_input_required_format'] = 'full_html';
$handler->display->display_options['defaults']['style_plugin'] = FALSE;
$handler->display->display_options['style_plugin'] = 'list';
$handler->display->display_options['style_options']['default_row_class'] = FALSE;
$handler->display->display_options['style_options']['row_class_special'] = FALSE;
$handler->display->display_options['style_options']['wrapper_class'] = '';
$handler->display->display_options['defaults']['style_options'] = FALSE;
$handler->display->display_options['defaults']['row_plugin'] = FALSE;
$handler->display->display_options['row_plugin'] = 'fields';
$handler->display->display_options['row_options']['default_field_elements'] = FALSE;
$handler->display->display_options['defaults']['row_options'] = FALSE;
$handler->display->display_options['exposed_block'] = TRUE;
$handler->display->display_options['defaults']['relationships'] = FALSE;
$handler->display->display_options['defaults']['fields'] = FALSE;
/* Field: Search: Node Index results */
$handler->display->display_options['fields']['node_index']['id'] = 'node_index';
$handler->display->display_options['fields']['node_index']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['node_index']['field'] = 'node_index';
$handler->display->display_options['fields']['node_index']['label'] = '';
$handler->display->display_options['fields']['node_index']['exclude'] = TRUE;
$handler->display->display_options['fields']['node_index']['element_type'] = 'h2';
$handler->display->display_options['fields']['node_index']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['node_index']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['node_index']['hide_empty'] = TRUE;
$handler->display->display_options['fields']['node_index']['link_to_entity'] = 1;
$handler->display->display_options['fields']['node_index']['view_mode'] = 'search_result';
$handler->display->display_options['fields']['node_index']['bypass_access'] = 0;
/* Field: Search: File Index results */
$handler->display->display_options['fields']['file_index']['id'] = 'file_index';
$handler->display->display_options['fields']['file_index']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['file_index']['field'] = 'file_index';
$handler->display->display_options['fields']['file_index']['label'] = '';
$handler->display->display_options['fields']['file_index']['exclude'] = TRUE;
$handler->display->display_options['fields']['file_index']['element_type'] = 'h2';
$handler->display->display_options['fields']['file_index']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['file_index']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['file_index']['hide_empty'] = TRUE;
$handler->display->display_options['fields']['file_index']['link_to_entity'] = 1;
$handler->display->display_options['fields']['file_index']['view_mode'] = 'search_result';
$handler->display->display_options['fields']['file_index']['bypass_access'] = 0;
/* Field: Node Index: Title (indexed) */
$handler->display->display_options['fields']['node_index_title']['id'] = 'node_index_title';
$handler->display->display_options['fields']['node_index_title']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['node_index_title']['field'] = 'node_index_title';
$handler->display->display_options['fields']['node_index_title']['label'] = '';
$handler->display->display_options['fields']['node_index_title']['element_type'] = 'h2';
$handler->display->display_options['fields']['node_index_title']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['node_index_title']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['node_index_title']['hide_empty'] = TRUE;
$handler->display->display_options['fields']['node_index_title']['empty_zero'] = TRUE;
$handler->display->display_options['fields']['node_index_title']['link_to_entity'] = 1;
/* Field: File Index: File name (indexed) */
$handler->display->display_options['fields']['file_index_name']['id'] = 'file_index_name';
$handler->display->display_options['fields']['file_index_name']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['file_index_name']['field'] = 'file_index_name';
$handler->display->display_options['fields']['file_index_name']['label'] = '';
$handler->display->display_options['fields']['file_index_name']['element_type'] = 'h2';
$handler->display->display_options['fields']['file_index_name']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['file_index_name']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['file_index_name']['hide_empty'] = TRUE;
$handler->display->display_options['fields']['file_index_name']['empty_zero'] = TRUE;
$handler->display->display_options['fields']['file_index_name']['link_to_entity'] = 1;
/* Field: Search: Excerpt */
$handler->display->display_options['fields']['search_api_excerpt']['id'] = 'search_api_excerpt';
$handler->display->display_options['fields']['search_api_excerpt']['table'] = 'search_api_multi';
$handler->display->display_options['fields']['search_api_excerpt']['field'] = 'search_api_excerpt';
$handler->display->display_options['fields']['search_api_excerpt']['label'] = '';
$handler->display->display_options['fields']['search_api_excerpt']['element_label_colon'] = FALSE;
$handler->display->display_options['fields']['search_api_excerpt']['element_default_classes'] = FALSE;
$handler->display->display_options['fields']['search_api_excerpt']['hide_empty'] = TRUE;
$handler->display->display_options['fields']['search_api_excerpt']['link_to_entity'] = 0;
$handler->display->display_options['defaults']['sorts'] = FALSE;
/* Sort criterion: Search: Relevance */
$handler->display->display_options['sorts']['search_api_relevance']['id'] = 'search_api_relevance';
$handler->display->display_options['sorts']['search_api_relevance']['table'] = 'search_api_multi';
$handler->display->display_options['sorts']['search_api_relevance']['field'] = 'search_api_relevance';
$handler->display->display_options['sorts']['search_api_relevance']['order'] = 'DESC';
$handler->display->display_options['defaults']['arguments'] = FALSE;
$handler->display->display_options['path'] = 'search-page';

Please use attachments for adding Views exports, this is otherwise a pain to scroll over.
Did this work for you in a previous version, too?
Also, I see you're using the search_api_multi module for creating the view, which is another matter entirely. Can you re-create the problem with a normal view, based on a single index's base table, too? Otherwise, we should either move this issue or create a new one in the search_api_multi project.

Sorry for the delayed response, I ended up just excluding the title and moving on, but I've just ran into this issue again and went looking to how I solved it and found this post again.

It does seem to be only related to using the multi-index approach, I created a view that uses just the single index and it doesn't occur.

Hm, OK, that's at least something.
Still, it might be the highlighting processor after all, just triggered by the multi-index view.
Can you see if the attached patch resolves the problem for you? (Not an actual solution, but just for finding out where the bug is.)

Oops, here's the patch.

It doesn't seem to have affected anything. I'm on Search API 7.x-1.22, Multi-index searches 7.x-1.4, Database search 7.x-1.6, Search views 7.x-1.22 if any of that matters.

I've attached a screenshot of what's happening.

Ah, now I think I've got it! Thanks for the continued feedback!
Patch attached, please test!

Ah, just had the wrong project set.

Committed.
A review would have been nice, but still, thanks again for your help!

Sorry for delayed response again. ಠ_ಠ I was wondering why I never get notifications on topics I follow, I had somehow turned off notifications by email in the "Issue notifications" tab of my settings... Anyhow, patch applied and working. Thanks!