I just had this issue today as well. The postmeta database table was still holding the post ID for the images that were being pointed to, which is why the button wouldn’t appear. I also did what slunt32 did, but it screwed up for me. So I just popped into MySql and ran an update on my meta_key to set it to ”. After that, it was fine.
If anyone could bother, you could always write …. ah, I just read acobster’s fix. Yeah, you could do that. Check the post id in the post_meta to see if the attachment url actually points to a media file.
Potato of Fortune,
Potato
