When getting closer to lights with a lensflare object, they can be seen though walls.
Here you can see where the lensflare objects are placed.
And now when running the game, everything is still alright
However, when I get closer, they appear.
At the moment of taking the screenshots, I had one post effect active (02_pp_fog_by_klepto.lua by shadmar) but after removing the effect the bug still occurs.