USD import for sk meshes aka nanite foliage, vertex data and uv2

Hello i’m trying to use vertex data on nanite foliage but the general sk mesh (trunk+instances) seem to ignore it.
This is imported via usd import.
The base trunk that is imported together shows the vertex data but it’s only a part of the whole asset.
I tried also to bring other uv sets, in Asset User Data > Primvar to UVindex but that seem to be completely ignored as well.
This is on 5.9
Any clue ? thx