I've been running into an odd problem on our WP blog that has me befuddled.
I custom built the theme we use and I enabled Featured Images by adding the following line to the beginning of the functions.php file:
add_theme_support( 'post-thumbnails' );
This has worked fine for a while now. The Featured Image checkbox appears in the Screen Options dropdown for posts and when checked, the Featured Image module appears in the sidebar. Perfect.
In the last month or so, the Featured Image checkbox option keeps disappearing from the Screen Options dropdown (as does the module).
Now in terms of getting it to reappear, I've only found one thing that seems to work: re-uploading the functions.php file. Keep in mind, I don't actually edit or change the file in anyway. I just re-upload the same version that's currently on the server. For some reason though, that causes the Featured Image stuff to reappear. At least for a while until it disappears again.
Any ideas what this is or how to fix it?