lighting bug making some surfaces invisible

[necessarily-equal]

On a test map I made, I managed to break the lighting by making a large ceiling with a light texture (not very bright, of luminosity 200).

An example of a broken platform:

An example of non-broken platform (on other side):

For looking at it quickly, I didn't notice a pattern of why some platforms become transparent, and why others don't.

Test map attached: map.zip

[slipher]

This repo is only about navmesh generation. The living q3map2 is in https://gitlab.com/xonotic/netradiant

[necessarily-equal]

https://gitlab.com/xonotic/netradiant/-/issues/160