RecastNavMesh is not generated at loaded sublevel

RecastNavMesh is not generated at the sub level dynamically added in C ++ in 4.20. In 4.18, 4.19 it was generated normally.

Probably, changes to the large number about NavMesh systems from 4.19 to 4.20 cause this issue.

This problem can be avoided by setting Runtime Generation of Navigation Mesh to Dynamic and placing NavMesBoundsVolume at a persistent level. However, from a performance point of view it is desirable to resolve in the state of Static

1. Open attached project in repro_0420.zip
2. PIE
3. Press "Map1" button to visible Map1
4. Check that RecastNavMesh-default is generated correctly
5. Press "Map1" button to invisible Map1
6. Press "Map2" button to visible Map2
7. Check that RecastNavMesh-default is generated correctly

result:RecastNavMesh-default is not generated for Map 2