Can't fix black hole (BSP cut)

Who knows how i can fix this?
I already tried to change order of brushes, convert them to SemiSolid / Solid, but no result... I even removed all NonSolid brushes from these rooms--nothing!
There is should be wall, but it disappeared. Very strange...
I already tried to change order of brushes, convert them to SemiSolid / Solid, but no result... I even removed all NonSolid brushes from these rooms--nothing!
There is should be wall, but it disappeared. Very strange...