So in all the hours that I've played this game, I never ran into the problem that nobody in the castle could move or enter the castle.
Yep, you heard that correctly, all AI ceased to work out of nowhere.
Then I deleted one Caged Crab.
He was just chilling, minding his own business.
He wasn't even in the way, he was just somewhere on the ground.
But his removal fixed the entire castle.
5/7, would find an edge-case bug for an 8 year old game again.