Quick answer: Unreal Procedural Foliage Volume corrupting placed instances after undo of a rebuild? Undo restores old foliage type refs but not instance positions - rebuild again to recover.
Tweaked foliage type, rebuilt the volume, hit Ctrl+Z. Half the placed trees disappear; the rest are mis-aligned.
Avoid undoing rebuilds
Treat Resimulate as a non-undoable operation. Save before resimulating; restore from save if you don't like the result.
Or rebuild after undo
If the undo happened, run Resimulate again. The volume regenerates from scratch; alignment recovers.
Use UFoliageInstancedStaticMeshComponent directly
For tight control, bypass the volume and place via the ISM component. Undo behavior is cleaner.
“Procedural systems and undo are awkward partners. The undo stack doesn't track procedural-state correctly.”
Build a 'snapshot before procedural op' habit. Reduces the recovery surface to 'restore the snapshot'.