Every time his head goes off screen, when he returns, he is headless for a bit. No idea if this somehow ties into the missing thralls on the great wheel or not.
Personally, I think wheels should stop if not actively training a thrall and even remove the thrall avatar if no thralls are inside at all.
That actually due to reducing server load cost. I was able to do that in a mod. But you see every new addition of code work you throw at server to client that just another ping. As simple as that effect would be. It would be a nightmare to keep it up. Also worth noting a nightmare to do a player version of that lol.