No Material on UHierarchical Instanced StaticMesh Component when used with runtime generated StaticMesh

Hi everyone,
We are facing problems with a Static Mesh created at runtime with a FMeshDescriptionBuilder;
but only if used on a UHierarchical Instanced StaticMesh Component.
The Geometry goes on video but the material is missing.
Everything works fine if i use a UStaticMesh Component with the same StaticMesh.
I am using the new UE5 early-access version, and StaticMesh, UStaticMesh Component and/or UHierarchical Instanced StaticMesh Component’s are all generated at runtime.

Is it a known issue? Do anyone knows anything about?