PackedLevelActors are not updated when changing some properties

Packed level actors may not be updated after changing certain properties.

Workaround: reload the level containing the PLA.

1. Create a packed-level actor from a couple of cubes.
2. Edit in-place and change the material of one of the cubes.
3. Commit changes.
4. Repeat step 2 and 3 again (changing material on the same cube).
5. Notice the material for the cube is incorrect.