[Plugin: Multiple Post Thumbnails] Upload boxes not displaying (fix)

I noticed that a few other people have been having problems getting the upload boxes to display on the edit post screen. Either the boxes don’t display at all, or they display in the wrong order, or only some display but not others. I think I may have a solution!

In the file multi-post-thumbnails.php, take line 83:

add_action('add_meta_boxes', array($this, 'mpt_add_metabox'), 12);

and move it after line 86, so it’s the last call to add_action() within the register() function. So far, this has entirely fixed the problem for me in 3.1.4. Definitely worth a shot if you’re having this issue.

http://wordpress.org/extend/plugins/multiple-post-thumbnails/