@Dejvvo @ZendSeeker Try this one see if that does the trick
r.RayTracing.Geometry.InstancedStaticMeshes.Culling 0
and potentially this one too r.raytracing.culling 0
we had to do this on this sample scene Hillside Sample in UE Feature Samples - UE Marketplace in this sample scene we had a similar issue with the glass and other ISMs and HISMs
