I am trying to create an outdoor map, but the skybox(2D) renders infront of the brushes. All brushes infront of the skybox are invisible. In a seperate, indoor room, the walls and stuff are fine. Entities are visible as well, but all brushes in the skybox, box, are invisible. Any ideas?

You could try searching first. That is a common problem, follow the idea of that post and it should be fixed.

Yeah, I actually did, found that post imediatley after posting. Wrong keywords