Last night I meet the Companion leader. One of the guys ask me to take a sword over to the blacksmith to be sharpen for one of the members. Anyway the blacksmiths hut is in the back up on a hill, except most of this area was invisible and directly under it was a massive whole in the map. When i got there it looked like he was floating in space. He came down on his own fortunately, I didn't want to see what happened if I tried to get to him.

Something similar happened to me but in a different game. Go back into the building where you met the leader. Then go back outside and see if that area is complete (hole is not there).