Cannot build HLODs with Hierarchical Instanced Static Mesh (HISM)

General Issues and Bug Reporting
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Reference ID

cb7337fe-4f68-c35d-27ee-bb9259b7bd14

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

World Building

Summary

After the v28.00 update, HLOD’s gave a validation error on launch. After attempting to rebuild HLOD’s, the output log gave an error pointing to the HISM’s placed with the foliage tool.

Steps to Reproduce

Place instances with the Foliage Tool in UEFN

Try to build HLOD’s

Expected Result

HLOD’s build without failing. It works if I remove everything placed with the Foliage Tool.

Observed Result

HLOD Build fails with the following error in the output log

Error: Ensure condition failed: BuiltInstanceBounds.IsValid || ClusterTreePtr->Num() == 0 [File:D:\build++Fortnite\Sync\Engine\Source\Runtime\Engine\Private\HierarchicalInstancedStaticMesh.cpp] [Line: 1993]

Platform(s)

windows

Additional Notes

This worked just fine before v28.00 update, no changes were made to the foliage to cause this to happen. I tried using foliage tool around the 0,0 point on the map to see if the error would still triggers and it does.

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Update:

After some more testing, the error only triggers if using either Instancing or Mesh Section HLOD Batching Policy. The error does not persist if set to None.

However, I need it set to Instancing in order for my materials to render. They render black if batching policy is set to None. This worked as expected before v28.00 update.