[wp-trac] [WordPress Trac] #52855: Block editor sometimes missing some theme_support sections of sidebar

[WordPress Trac]

#52855: Block editor sometimes missing some theme_support sections of sidebar
--------------------------+-----------------------------
 Reporter:  joyously      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Editor        |    Version:  5.7
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 The block editor is sometimes missing sections in the sidebar related to
 what the theme supports, like page templates and featured image. It
 appears that post formats are unaffected, and also wide-blocks (which
 isn't in the sidebar, but is theme_support related).

 According to replies to this forum topic
 https://wordpress.org/support/topic/theme-support-for-post-thumbnails-
 stopped-working-after-upgrading-to-wp-5-7/
 it is sometimes a JS error in unrelated code, but sometimes the existence
 of the theme's index.php file. A few users indicate it must be something
 else.

 Steps to reproduce the effect of index.php:
 1. Using WP 5.6.x, activate a theme that supports featured images, such as
 Twenty Twenty.
 2. Edit a post or page.
 3. Note that the featured image (or page template) section is in the edit
 sidebar.
 4. Rename the theme's index.php to testindex.php.
 5. Repeat steps 2 & 3.
 6. Update WP to 5.7.
 7. Edit a post or page.
 8. See that the featured image (or page template) section is missing.

 These steps repeated with the Classic editor show no missing sections.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/52855>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform