Path tracer stuck at 0% (not working) when viewing MetaHuman at LOD0?

[georgff1 (georgff)]

Hi there! The Path Tracer does not seem to work when I am near my Meta Human (LOD0, 1). It just flickers wildly, and the red bar stays at 0%. When I scroll away or turn the viewport away from the Meta Human it works fine. The GPU is at 90-100% load, the frames drop to 5fps and the path tracing doesn’t kick in.

It just looks like this:

At LOD3 it works fine:

I’ve tried to make the lights brighter. I’ve tried to restart the engine multiple times. I enabled ray tracing in the settings according to the tutorial by William Faucher. Tried to export but can’t even get one frame to be saved. I have OptiX Denoiser enabled.

(Config: Ryzen 7800 & RTX 4080. Studio Driver for the RTX. Unreal Engine 5.3.)

What am I missing here?

[georgff1 (georgff)]

I figured out a solution. Sadly, I don’t understand fully why it works, but it does:

1 - Make sure all static meshes have nanite disabled.

You can filter by the asset type in the content browser, then select all and disable nanite with right click → Nanite → Disable for selected.

2 - When you get an error, this clears the log:
r.Nanite.ProjectEnabled = false
r.Nanite = 0

[Alesdanz]

In my case the problem is Heterogebeous Volume
To Solve the problem

To activate: “r.PathTracing.HeterogeneousVolumes 1”

Or simply delete it “HeterogeneousVolume”