Lighting 'clitching' through walls.


I’m having this small problem with a blockout I made in 3DSmax. Since it’s a blockout and I wanted it to be procedural. So, I used a Loft system to construct the blockout. I also used a Shell modifier on it just to be sure the light wouldn’t ‘clitch’ through it due to the backface culling. (But this sadly didn’t work.)
I also converted everything to an editable poly, reset the normals and Xform. I also screwed around with some of the settings of the mesh and light in Unreal but so far, it didn’t really work. I’m hoping someone here knows how to solve this.

I mostly make natural, open world environments. So I have no clue how to solve it. (Or I’ve already tried the things I knew).
If someone could help me out here, that would be much appreciated!