have a look please.
This should go in a new thread in Support.
Please don’t post support requests in the wishlist thread (and not in the sticky as you have either).
-Jeremy
thats known behavior.
Some call it a bug, others call it bad asset creation if you just stick models into other models.
There are at least 2 threads already on this effect
Double-lighting artifacts on self intersecting geometry is a known problem on Windows. We’re working on a fix.
Try to turn of pixel light and it should go away.