Transparancy glitch depending on angle of view

[HikeAndMap]

The zip files for this can be found in the report I made here:
#229

Note in the image below the transparent area, looking through what's a wall in reality and to the best of my knowledge I did map it to represent a solid wall.

So I think this is just a glitch depending how one rotates it's solid from one viewpoint but transparent from another.