I have custom VILLAGER entities (NPCVillager.class) in my world which are managed by an NPCManager class. Using NMS I have made these VILLAGERs un-able to move. The problem is when I move far away from them and then return to them, they appear to have lost this custom NMS property and start walking around. It's as if they've reverted to the parent class EntityVillager. What's going on?