Editor 'Build All Levels' discards Volumetrics Lightmaps in persistent level

Building the level or lightmaps can clear the volumetric lightmap.

In 5.5, this requires you to perform a full build, or a lighting only build with a BSP brush in the scene.
In 5.6, all level builds or lighting builds with BSP brushes in the scene will clear the all lightmaps, and even marks some of the primitives as unbuilt. Further lighting only builds will not restore the lightmaps (volumetric or otherwise).

Also tested on UE5/Release-5.5, CL: 41545209

1. Download the attached test project and open.
2. Enable "Show->Visualize->Volumetric Lightmap"

Unreal Engine 5.5.4, CL 41545209:
3. Run "Build->Build Lighting Only"
4. Observe that the sphere "Sphere" is lit, and the Volumetric Lightmap probes are visible.
5. Run "Build->Build All Levels"
6. Observe that the sphere "Sphere" is black, and the Volumetric Lightmap probes are gone.
7. Repeat step 3 to restore the Volumetric Lightmap
8. Add a BSP brush to the scene, such as the Spiral Stair (Place Actors->Geometry->Spiral Stair"
9. Repeat step 3 again, "Build->Build Lighting Only"
10. Observe that the sphere "Sphere" is black, and the Volumetric Lightmap probes are gone.

Unreal Engine 5.6, CL 42433086:
3. Do not save during this process - restarting the editor is a later step to restore the default state
4. Run "Build->Build Lighting Only"
5. Observe that the sphere "Sphere" is lit, and the Volumetric Lightmap probes are visible.
6. Run "Build->Build All Levels"
7. Observe that the entire scene has become black, and that it is now reporting that there are unbuilt light interactions
8. Repeat step 3, "Build->Build Lighting Only"
9. Observe that the entire scene is still black, and the unbuilt light interactions remain
10. Restart the editor to restore the map and built data to its original condition
11. Add a BSP brush to the scene, such as the Spiral Stair (Place Actors->Geometry->Spiral Stair"
12. Repeat step 3 again, "Build->Build Lighting Only"
13. Observe that the entire scene has become black, and that it is now reporting that there are unbuilt light interactions
14. Delete the BSP brush
15. Repeat step 3 again, "Build->Build Lighting Only"
16. Observe that the entire scene is still black, and the unbuilt light interactions remain