I did a restore and waited for messages to finish indexing. When it said it was finished, I looked in the photo gallery and there are some but certainly not all photos. Lots of blank squares. Spoke to Apple and was told it’s an indexing bug in iMessage and wait for a fix.
iMessage photos are so unreliable that now I download and save the ones I want and give up on the rest. I know they are in the thread but they are not showing in the iMessage photo gallery
I even deleted one entire thread and started a new one for one contact and the same problem with photos remains. New photo as of yesterday is in the thread but not in photos gallery under the photos tab. Tried having a screenshot sent to me. Same thing. Doesn’t show in photos tab
I hope yours works after it finishes indexing but don’t be surprised if it doesn’t