.Map :: MoHAA Mapping

i've put this wall (see picture) in my map, in a staircase.

and some of it disappears. and u can see right through it. i tried to replace the wall, i check if theres any caulk but no. (u cant shoot through the missing wall)

its the only thing that preventing me from finishing my map.
its not really bothering me, but i rather have it gone.

Why do you have a wall behind a wall?

Anyway it could be a broken brush:
select the "invisible wall" in radiant, and press ctrl + G, it will put the corners of the brush on grids, if this doesn't work, check if an other brush is hitting the invisible brush, sometimes this will also make a piece of a face invisible.

k, i just closed the wall behind the missing wall and the texture got back