39.67.5 Occlusion/Imperfect cutaway on player build structure

[Leoquent]

The cutaway algorithm is missing some essential walls on my player build structure leading to some obstruction.

It seems to be directly tied to stairs and structures above them.

 

I'll add some screenshots of the problem. Hope the green markings help understanding the geometry.

 

The three tile wall in screenhot A is the biggest problem. It is always fully opaque (when I'm on ground floor) and completely blocks the visibility of a substantial part of my space.