Raytracing light glowing through surfaces

I’ve been trying to get RTX global illumination to work in my scene, and although it’s working, the directional light is shining through my walls/ceilings. Not in the same way that light bleeds through meshes when they have no thickness, or bad lightmaps etc, but actually lighting up the entire surface. You can see an example in the image. I’ve already tried advice from a really helpful guy on Polycount, but with no luck in the end. Here’s the Polycount thread so you can see what I have tried already: Raytracing GI lighting incorrectly — polycount

Thanks in advance, I really appreciate anyone taking the time to help out!

But shouldn’t the light be even between that roof and the adjacent wall? The problem is that global illumination is working fine on the wall, but the direction the light is coming from is causing the underside of meshes to light up. I think this screenshot better illustrates the problem. The directional light is pointing in the direction from behind this wall and the light is coming through the mesh, technically the wall should be completely in shadow. What’s happening doesnt seem to have anything to do with bounces