Having the same problem! For a while it still worked fine when I loaded in (except for the invisible floor), but now it's giving me this error too. I even have the zm nuked actor on the map.... so confused

In radiant, all of my textures/terrains show up fine, lighting is great, but when I run the map, I have no walls, ground, floor, etc. All models, fx, structs, etc are still there. The only other thing not working is that I can't knife zombies, and they can't hit me. Shooting them works fin...