[wp-trac] [WordPress Trac] #52818: Ordering metaboxes broken in WP 5.7

[WordPress Trac]

#52818: Ordering metaboxes broken in WP 5.7
--------------------------+-----------------------------
 Reporter:  terraling     |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Editor        |    Version:  5.7
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 Post edit screens with metaboxes allow for drag and drop re-ordering.

 This worked up to WordPress 5.6.2, but stopped working in WP 5.7, though
 it continues to work if you use the Classic Editor to edit posts rather
 than the block editor.

 When re-ordering the metaboxes, an ajax update with the action 'meta-box-
 order' occurs, and this reports a succesful response both in the working
 and non-working cases, so it ''appears'' as if updating the metabox order
 works.

 But, when the page is reloaded, the metaboxes are displayed in an
 unchanged order.

 For testing you can use the following code to register two dummy
 metaboxes:

 {{{#!php
 <?php
 /**
  * Add two dummy metaboxes to post edit screens
  */
 function xyz_init_meta_boxes(){
         add_meta_box(
                 'metabox_id_1',
                 __( 'Metabox One', 'textdomain' ),
                 'xyz_metabox_callback',
                 'post',
                 'normal',
                 'low',
                 array( 'foo' => 'One' )
         );

         add_meta_box(
                 'metabox_id_2',
                 __( 'Metabox Two', 'textdomain' ),
                 'xyz_metabox_callback',
                 'post',
                 'normal',
                 'low',
                 array( 'foo' => 'Two' )
         );

 }
 add_action( 'load-post.php', 'xyz_init_meta_boxes' );
 add_action( 'load-post-new.php', 'xyz_init_meta_boxes' );

 function xyz_metabox_callback( $post, $metabox ) {

         $foo = $metabox['args']['foo'];
         echo "<p>Content of metabox $foo</p>";
 }
 }}}

 To reproduce, with WP 5.7 edit a post using the block editor.
 Re-order the two metaboxes and update the post.
 Reload the page.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/52818>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform