Wow, I wonder if the same issue exists in the "Image Capture" app which I've used for years on my old MacBook to transfer photos off my iPhone. I would transfer everything off and occasionally find that some photos are inexplicably corrupted. The app itself is terrible, it regularly shows it imported an image but didn't, or it arbitrary imports a couple images completely randomly NOT from the ones I selected, so I end up with weird duplicates and stuff. :\