RecastNavMesh - Agent Height changes back to default value after project restart

When trying to change the value of Agent Height under RecastNavMesh-Default it will change back to its default value when you open back up the project.

1. Create a new 4.18.2 project and add a NavMeshBoundsVolume to the map
2. Click on RecastNavMesh-Default in the World Outliner and go to Generation> Agent Height and set it to 2.
3. Open Project Settings>Engine>Navigation Mesh and make sure that the Agent Height is also set to 2 under Generation
4. Save, close, and re-open the project

Result: RecastNavMesh-Default Agent Height changed back 144 (default value)

Expected: RecastNavMesh-Default Agent Height stays at 2