Doesn’t matter what size wheel of pain the same thing happens. I fill it full of gruel, drag a thrall back and see the greyed out icon for the thrall and hit the start arrow. The thrall starts on the wheel for 3-5 seconds and disappears. The wheel of pain looks like it is working but the thrall never trains. I left a Level 1 Thrall on the wheel for 5 days still sems stuck. Needless to say, I cannot train anyhing and it is very frusterating.
Singleplayer?