Lighting is not appearing ingame but is working perfectly fine in Radiant. Is there any reason this may be occuring? (I'm talking about omni lights or spotlights, not the "sun" light. The sun is working perfectly. Just not the rest of it.

I have this same problem and it's very depressing. Can someone please help us find a solution? Same issue: Radiant is absolutely fine whilst modifying things etc. but when you go ingame the textures for all floors, walls and ceilings are invisible. What have we done to fuck this up?