GPU Lightmass Static Meshs not casting Shadows (UE 5.4.3)

Development Rendering
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1

Hello Community,

I am relatively new to Unreal Engine development, and I am having issues with the GPU Lightmass light baking.
The difference between CPU and GPU Lightmass is pretty big, and I don’t understand what I am doing wrong.
I have looked through the forum and tried a lot of what people suggested.
I have made sure all the meshes have “Cast Shadows” and “Static Shadows” checked.
I have also changed the lighting map override size to a bigger resolution.
I have made sure that lumen is completely disabled, and hardware raytracing support turned on.

I can bake the lighting with CPU and it turns out fine, but it takes significantly longer than my GPU.

System:
CPU: AMD Ryzen 7900x
GPU: AMD Radeon 7900xtx

Before any baking:

image
image516×691 66 KB

GPU Lightmass baking:

image
image763×735 48 KB

CPU Lightmass baking:

image
image792×765 40.1 KB

Any direction would be greatly appreciated.

2

Are the walls and floor static meshes, or brushes?

3

All the meshs are static, and the lights are also static.

4

My question is about the actor type, not the mobility. Static meshes are an actor type.

5

My apologizes.
They are just static meshs actors, not brushes.

6

It looks like they are not building surface lightmaps at all, even the walls don’t have any of the light from the cone.

When this only happens in GPU lightmass it is usually because the geometry type isn’t supported by hardware raytracing (brushes, procedural meshes, spline meshes, etc.)

example:

image
image922×726 47.4 KB

Left: Static mesh
Right: Box brush

Since you say these are static meshes I’m not sure what the cause would be honestly…