I'm using the Meta Box AIO plugin, and I'm creating a custom post type. I'm also using the Classic Editor plugin. However, when I create a new custom post type using the MB Custom Post Type, it won't show the featured image input on the post edit page for that post type. I read this forum post that seemed to be the same problem: https://support.metabox.io/topic/show-wordpress-featured-image/
In that post, the user was instructed to enable "Featured Image" from the "Supports" section. However, "Featured Image" isn't an option. "Thumbnails" is an option, but making sure that it is checked doesn't enable the featured image upload area either. Any ideas?