Apple Watch Photos face not working

I’ve had the same photo album from my

iPhone synced to the photos watch face for a long time. All of the sudden, the watch face tells me “No photos” and to use the app to sync an album. If I switch it to another album, the other album works. When I switch it back to the original album, I get the “No photos” message again. Help?

Also I guessed when selecting series 4. I have no idea what series my watch is and no clue how to find out. It doesn’t seem to say that in the “about” section in general settings, but the software is 8.1.