[LVL ED] Why do Entities get Stuck?

[Cranky Old Man]

Ok, so I'm making a map, and I thought I'd make the map look better by adding some chairs, and debris on the floor. However, when I try the map, the entities get stuck in the floor planes. I tried lifting them off the ground a little bit just to be safe, but the same thing still occurs.

Strange thing is that, most of the other places in the same map don't experience this problem, it only seems to happen in this particular room/floor plane.

I don't know anything about caches, but try deleting the map cache.