Seems the shared album suddenly stopped updating photos. I don't know what happened. But near that time it told my my iCloud storage was full. I since deleted some files, and now have gigabytes free. Still however the album isn't updating. And I don't even know for sure iCloud storage factors into shared albums, because if it did, it should show a large chunk of iCloud space being used by photos, and it shows nothing.
Any help appreciated.