My game uses LoadLevelAdditive() to load levels in and out of the same location in a persistent scene. Each level has its own NavMesh. Switching out the level results in multiple NavMeshes laid on top of each other, overlapping. I can use NavMeshBuilder.ClearAllNavMeshes() to clear the existing NavMesh before loading the next level, but NavMeshBuilder is a UnityEditor class and can’t be used at runtime. Is there an equivalent function or some method to achieve this? Switching LoadLevelAdditive() to LoadLevel() is not an option for us, so the only other workaround I can think of is to load in a single persistent NavMesh and have each level use NavMeshObstacles to dynamically carve out the desired mesh, which seems like a hassle and maybe not very reliable…
Try to use the addition navmesh tools found on the github. With these you can add a navmesh surface to what surfaces you want to use so you can turn the navmesh into a prefab.