I have a custom post type called Slide set up:
register_post_type('slide', [ 'labels' => [ 'name' => __('Slide'), 'singular_name' => __('Slide'), ], 'public' => true, 'has_archive' => true, 'capability_type' => 'post', 'capabilities' => array( 'create_posts' => false, ), 'map_meta_cap' => true, 'menu_icon' => 'dashicons-universal-access', ]);
I then have a custom taxonomy for it, called Group:
$groupLabels = [ ... ]; register_taxonomy('Groups', 'slide', ['hierarchical' => true, 'labels' => $groupLabels]);
This works fine - I can create Groups, nest them, and tag a Slide with them. The problem is when I go into the edit page for a Slide ( /wp-admin/post.php?post=202&action=edit ) and select some Groups then save it, the Groups I selected float to the top of the list, out of hierarchy order. The weird thing is if I go to the Quick Edit (while still on the list page) it displays correctly.
Does anyone have ANY idea what's going on? I don't even know where to start looking, and Googling for anything like this just brings back completely unrelated results because it's too specific.