Quick answer: Unreal PCG-generated ISM exceeding the per-component instance limit? Engine caps; split into multiple ISMs.
100k tree placement; PCG creates one ISM; engine error: instance count exceeds 65536.
Configure PCG batch size
PCG output node > Max Instances per Component. 32768 is safer.
Or split by region
Per-chunk ISM. Naturally chunked by world position.
Use HISM with culling
Hierarchical ISM with built-in culling. Higher cap; more efficient.
“ISM has per-component limits. Mass instancing needs chunking.”
If your PCG produces many instances, the chunking is mandatory. Document.