Breaking a Level Instance resets InstancedFoliageActor foliage to world origin (0,0,0)

Summary

When you Break a Level Instance that contains painted foliage (an AInstancedFoliageActor),
all foliage instances belonging to that actor collapse to the world origin (0,0,0) instead
of staying at their painted world locations. Every other actor in the Level Instance keeps
its correct transform; only the foliage is affected.

What Type of Bug are you experiencing?

Editor

Steps to Reproduce

  1. Create a Level (or Level Instance asset) and paint some instanced static-mesh foliage
    inside it (on a mesh or landscape belonging to that level).
  2. Place the level as a Level Instance in a persistent world at a NON-identity transform
    (i.e. move it away from the world origin).
  3. Select the Level Instance and choose “Break”.
  4. Observe the foliage from that level.

Expected Result

After breaking the Level Instance, the foliage stays at the same world locations it had
while the Level Instance was intact.

Observed Result

The AInstancedFoliageActor’s foliage instances all snap to the world origin (0,0,0)
(offset by exactly the former Level Instance transform). All other actors are unaffected.

Affects Versions

5.8

Platform(s)

Windows