LL CC exports (saves) images always with the error message "some export operations were not carried out" ... the saved photo will be exported anyway. Now LL CC photos do not export anymore! Only the small bar at the top left shows "Is stored ..." ... Nothing happens!
Same thing happened to me - when you "edit in" Photoshop (on an iPad), it saves the image as a PNG. LR CC doesn't allow you to "export" (as it was originally called) a PNG. So those edited files cannot be saved. This is very confusing - I liked it the way it was because it would update on my desktop and then I was able to go back and forth between my desktop and iPad and be able to export all onto my desktop.