I have problem with compilling of my map! I was working on terrain, everything was ok, but suddenly, when I added 16 (!) brushes, some of the old brushes (in red circles) gone "invisible" but still making collide. Does anybody know what, the hell, is happening? I did nothing with this brushes, I was working in absolutely different part of the map and anyway, this happend with brushes which were no edited and were ok one compile before.
Make a backup of your current map, so you can experiment without losing anything.
In a copy of the map, delete the recent brushes you added. Does the problem go away? Then you know that the brushes you added caused the problem, and that there's something wrong there.
If the problem doesn't go away when you delete the recent brushes you added, then, yeah, try just deleting and remaking the brushes that have visual problems...but it sounds like something's wrong with your recent changes...
I used to run into this problem when I had too many split faces in my terrain. Make sure you split brushes up into triangles before you do any odd vertex manipulations that will split a face into two planes.
