I had a dozen or so images on a portable (external) drive in a catalog with about 70 images on another drive.
When the drive wasn't plugged-in (not available) I tried to "remove from catalog" these ~dozen images. This worked for all but three images which refused to be removed from the catalog. I tried all sorts including an update the came out while I was working on the problem. Finally I did the only obvious thing left and plugged the external drive back in - "remove from catalog" worked straight away.
Thankfully I was in the situation where I had the external drive, if I had done something like move the images I think I'd be stuck with a catalog that would have to be trashed/rebuilt.
Regards,
Peter Stagg
