I deleted the data in the gallery app. I then restarted. It does muck up your folders a bit, but photos are unaltered. You also have to reset Gallery Labs if you use that.
Animation is essentially a wee hop. Every so often after some persistence a photo will open. Selecting never works.
FYI I'm not a novice so cache cleaned, full restart etc. Still no improvement. More interested in folk who have the same issue and if there's a specific resolution tbh. Thanks anyway...
I deleted the data in the gallery app. I then restarted. It does muck up your folders a bit, but photos are unaltered. You also have to reset Gallery Labs if you use that.