Extra Material slots on HierarchicalInstancedStaticMesh Components when using LOD'd Static Meshes.

When using a static mesh with multiple LOD’s attached inside a HierarchicalInstancedStaticMesh BP Component, the HISM is adding extra Material Slots to itself. The extra slots occasionally change in amount and location in the list, though I haven’t figured out what is making this change. This is making swapping in dynamic materials really awkward. One of these in our current project has 11 slots for a static mesh with 7 materials.

Repro Steps:

  1. Import a Static Mesh.
  2. Add extra LOD’s (I used 3)
  3. Assign material for easier viewing.
  4. Create new Actor BluePrint
  5. Add HierarchicalInstancedStaticMesh component
  6. Set HISM static mesh to your imported Static Mesh
  7. View Material List on the HISM
  8. Notice extra material slots have been added. (In my test case 1 extra at Element 1)

Hey ,

Thanks for the clear and precise repro steps. I was able to confirm what you are reporting and have gone ahead and entered a bug report for the issue. You can track the issue following the link below on our public issues tracker.

UE-37474

Once the issue has been addressed by our engineers either myself or another staff member will return with an update.

Let me know if you have further questions or need additional assistance.

Cheers,

Andrew Hurley