Light bleed through mesh

Hell all I have a modular system that generates walls and floors of rooms randomly using Hierarchical Instance Static Mesh Components. For some reason when light is present in the level(necessary) it bleeds through surrounding walls.

Things I’ve tried:

Many light and shadow settings being changed(shadow bias, shadow resolution, static/dynamic shadows)

Turning off/on lumen

Making material double side

Setting higher shadow and light resolution

The mesh is 50cm thick much higher than what is recommended.

Any help appreciated this is quite annoying.