Cool, thanks for figuring out the problems and yeah the Can Ever Affect Navigation is the flag you need to use to determine if the navmesh would be affected by the props or not, even if it’s only a 3D icon in the world.
When there’s a moving object in the world, it’ll try to have the navmesh calculated to try to regenerate the proper navmesh to avoid NPCs being blocked by the object, so you are right in your case you’ll see the navmesh keep being updated.
Additionally, once you perform the fix, is the Patrol Path working properly now and your NPCs are following the right path that you’ve designed?