I love this game but starting level 4 it got a bit buggy. When I'd press the arrow keys it would move only a tiny bit and then stop. It won't go away until I restart the camera, then the issue would re-appear shortly after. Once in level 5 even a restart doesn't help anymore. See the video, I'm always keeping the button pressed and not letting go unless I hit the other button.

I know using the main dial or the top dial is an option too, but have you ever tried to play with that? It's near impossible. Camera is a EOS 70D.
A really cool idea would be to be able to use the touchscreen. Maybe just touching the right side of the LCD "emulates" the right key, and the left side the left key.
Edit: After leaving the camera on for a bit but not doing anything on it, it was working again int he same level. However after 1-2 minutes of playing (same level still) the lag appeared again, making it impossible to continue playing.