Child actor references appear to be lost when restarting the editor

Child actor references appear to be lost when restarting the editor when added to another actor via a child actor component

1. Create blank project
2. Create actor blueprint "Parent"
3. Create actor blueprint "Child"
4. Add child actor component to "Parent" and assign "Child" as child class
5. Put an instance of "Parent" into the map
6. Drag the "Child" instance from the world outliner into the level blueprint to create a reference to it
7. Save map
8. Close editor
9. Reopen editor
10. Notice that the child actor reference now says unknown

Expected: The child actor reference would retain a reference to the child actor component in the level
Result: The child actor reference appears to be lost after restarting the editor