It looks to me like the sim is standing on a platform, surrounded by a half wall, is that correct? Have you tried deleting the section of half wall between the platform and the ladder? I don't know for sure, but that seems like something that might result in a routing error. Let us know if that changes anything. Also, did you use the moveobjects cheat at all in this build? It might be helpful if you shared the build on the gallery and linked to it here so that other people can test it in their own game and see if they can figure out what's going on.