My browser console throws errors with status code 400 when it requests URLs like the below ones, when editing a custom post:
Because of this, I can't assign taxonomy terms to the post, because the box does not auto-populate as I type.
The problem does not occur when I edit a post type with no custom fields or taxonomies involved.
The problem does not occur on another website on the same server without Meta Box.
This is MB 5.4.6 and MB AIO 1.16.2.