Judy has a 15" MacBook Pro Retina, but she's been having issues that Apple Support can't solve. She can't edit any photo in Apple Photos. Apple thinks it's a software problem. Leo thinks this is a problem with the cache. Leo suggests exporting out all of her photos into another folder and move that to the desktop. Then she can delete the Apple Photos library and reimport her images. She should make sure it's the unmodified original, and not the thumbnails. Chances are, Judy's photo library became corrupt. It may also be a bug in Apple Photos, as indicated in this Apple Discussions thread.