How do you get your NPCs unstuck from a wall? Does leaving the map work? That bug is absolutely ridiculous.
Happen to my character, but I manage to wriggle myself out of it. Teleport works, and leaving the map may work also.
So it's not just me! Was it Virgil the Dumbass who turned into a wall? That's happened to me many times, and I haven't tried going back to the world map to see if he'll reappear. I actually had a similar problem with Jormund. In Qintarra, he turned invisible. His portrait remained, so I clicked on it. Jormund had become a wall. Couldn't speak to him or check his inventory. Finally I just left the city for the world map. First random encounter...Jormund's back! Maybe it'll work for other followers.
Sounds hopeful, thanks guys. Also, I've seen it happen with enemies too. Actually, it seems like people get stuck WAYY too much in Arcanum. Come on, that never happened in fallout!