Disabling World Partition causes all actors to be removed from level after save & reload

1. Create and open a new level from the open world template (or use any existing world partition level)
2. Add a few actors to the level, and save it. 
3. In World settings, uncheck "Enable Streaming", then click the "Disable World Partition" button.
4. Observe that the actors are still present in the level
5. Save and reopen the level
6. Observe that the level is now empty.

UE5 - How to disable World Partion?