When I load my levels, I get some warning lines in the output log.
LogActor:Warning: RecastNavMesh /Game/Levels/DenaliMaster.DenaliMaster:PersistentLevel.RecastNavMesh_0 has natively added scene component(s), but none of them were set as the actor's RootComponent - picking one arbitrarily
I have received confirmation that this error can be safely ignored. I have checked in 4.11, and it seems that the error has been resolved in that version.