After 2 years of having this issue, I finally figured it out. So lastnight I got really annoyed with having all 3000+ of my pictures blurry and not being able to upload, view or share them because of the exclamation mark. I went over into the section that says "Photos" and at the bottom I realized that it said downloading paused because phone is saving battery power" MY LOW POWER MODE WAS ON! As soon as I turned it off, all the pictures started to go back to their original setting. They werent blurry or anything. So I think the trick is if your photo settings is set to iCloud Photo Library, Download and Keep Originals The phone is trying to download all the originals into your icloud, and low power mode prevents that from happening because it pauses the download. So, my advice is to keep your phone off of low power mode especially while its uploading new pics. Hopefully this will help you as much as it has helped me.