field_ui doesn't show existing fields without instances

In some cases there are fields that have no instances. Then the field_ui fails to show them under "Add existing field" and it's not possible to create instances for these fields using the UI.

Steps to reproduce

1. Create a field without an instance. For example using this code
   

   $field = [
     'field_name' => 'field_no_instance, 
     'type' => 'text', 
   ];
   field_create_field($field);
   

2. Navigate to "manage fields" on any code content type.

Expected result

The field shows up in "Add existing field".

Actual result

The field doesn't show up in "Add existing field".