I am finishing up a multi-author site (my first) and came across this problem with uploaded images.
When logged in as an Author, users can only make changes to images - Edit Image, Title, Alt, Caption, etc. - when first uploading their images. Once an image or images have been uploaded and attached to a post (a custom post-type in this case), any changes to the aforementioned text fields will not be saved, and the Edit Image button brings up an Ajax loading .gif for a moment then displays '-1' where the thumbnail was.
The site is currently running on 3.3.2. I've disabled all plugins and stripped functions.php to just the bare minimum and the problem remains.
When a user is logged in as an Editor or Admin, this problem goes away.
I haven't been able to find much information on this problem. Anyone else have some experience with this?