Quick answer: Unreal foliage painted in Procedural Foliage Volume leaves orphans after volume deletion? Foliage instances belong to the world, not the volume - clean via Resimulate or remove from the ISM directly.
Deleted a Procedural Foliage Volume. The 8000 trees it placed are still there but no longer tied to anything.
Resimulate the volume
Select the volume, Resimulate. The volume re-evaluates and removes instances that no longer belong.
Or remove via ISM
Find the InstancedStaticMeshComponent holding the orphans. RemoveInstance in bulk; commit the level.
Use Foliage Type filtering
Each instance has a FoliageType reference. Filter by type, remove all matching - cleaner than per-instance.
“Procedural Foliage paints world-owned instances. Volume deletion doesn't reclaim them.”
Treat procedural foliage like a generator, not a binding. Save the resimulate as part of your level cleanup checklist.