I’ve asked this question before and I’ve recreated my problem.
When I import my static mesh the direct light isn’t casting shadows correctly (as attached). Curiously, a skylight seems to be accurate (as attached).
At the moment the walls are just planes. I’ve established if I give thickness to the walls in 3ds Max, and reimport it lights correctly. I’ve selected “double sided geometry” in the content browser but it doesnt make a difference.
The obvious answer would be to give thickness to all my plane geometry but that would require me to adjust the UV’s to give more space to the geometry visible and I’d like to have the process of importing meshes as seamless as possible.