Views field token replacement patterns aren't showing in area handlers admin form

I have the same issue, except I can't use the tokens that aren't shown.
This also happens when editing the view Title.
If I use the token before adding the Contextual Filter, it works even after I add it.
If I edit the Title, or Header and save, they stop working (displaying {{ title }} instead, for example), and I have to temporarily remove the contextual filter if I want to add these tokens again.

This is because the code to make the list of tokens is arranging them into groups, but then clobbering each group:

      foreach (array_keys($options) as $type) {
        if (!empty($options[$type])) {
          $items = array();
          foreach ($options[$type] as $key => $value) {
            $items[] = $key . ' == ' . $value;
          }
          $form['tokens']['tokens'] = array(
            '#theme' => 'item_list',
            '#items' => $items,
          );
        }
      }

$form['tokens']['tokens'] is getting set each time, so earlier $type lists (where $type is fields, then arguments) get clobbered.

Patch coming.

Here's a patch.

This affects all area handlers that use TokenizeAreaPluginBase, so the unfiltered one too.

Fix looks great, but this still needs tests.

Test and fix.

Bug fix, so this can go against 8.2.x

The fix looks perfect for me!

1. +++ b/core/modules/views_ui/src/Tests/TokenizeAreaUITest.php
   @@ -0,0 +1,46 @@
   +
   +  /**
   +   * {@inheritdoc}
   +   */
   +  public static $modules = ['entity_test'];
   

   I like that we don't use node but rather the test entity type.

2. +++ b/core/modules/views_ui/src/Tests/TokenizeAreaUITest.php
   @@ -0,0 +1,46 @@
   +    $default = $this->randomView([]);
   +    $id = $default['id'];
   +    $view = View::load($id);
   

   Its kinda funny how bad this API is :)

Committed/pushed to 8.3.x and cherry-picked to 8.2.x. Thanks!