I am assuming that the functionality for navmesh rebuilding in the navmesh content example is meant to demo the dynamic navmesh building (the last sample with the movable blocker), however it only updates the navmesh during non-simulation/play modes. So basically moving it and the navmesh updates fine, but run simulate and do the same thing and the navmesh doesn’t change.
bRebuildAtRuntime Must Be set to True Inside 4.0 > Engine > Config > “BaseEngine.ini” for it to work properly in Simulation Mode. There is still some time when the NavMesh doesn’t Update on objet “Simulating Physics” (especially when the object gets too far away from the ground, than falls back, from what I saw), but it works great on movable Objects.