missing thumbnails on iPad for photos taken on iPhone

I have iOS 11.2 and an iPhone 7 and a one+ year old iPad. All pictures taken by the iPhone are showing up correctly on my MacBook Pro, but on my iPad several thumbnails are missing. On those photos the Edit option is also missing, although I can bring up the photo and look at it, even without a thumbnail. Is there a way to restore the thumbs? I tried the awful option of turning off iCloud photo library option, and then turning it back on, and when the updating was finished, there were fewer bad thumbnails, but there were still some.

Does anyone know how to restore a single thumb on iOS. Plenty of people discuss this for MacOS, but not for iOS 11.2. The problem was there on 11.12 as well. Thanks for any help.