I am working on a tactical cover generator using the native navigation mesh as the basis for the calculation.
So far, so good!
But as I wanted to add support for dynamic re-generation, I realized that you were providing a delegate to notify us when the navigation mesh was rebuilt: UNavigationSystem::OnNavigationGenerationFinishedDelegate
It works, but forces me to regenerate the information for the whole navmesh.
It is good enough for a small mavmesh, but when you have a map of the size of a city… 
The RecastNavMeshGenerator knows which tiles are getting rebuilt via PendingDirtyTiles and RunningDirtyTiles, but those are not accessible.
It also has an editor only member, RecentlyBuiltTiles, but not directly accessible and anyway not even present in a packaged game.
Is there currently a way to get the list of tiles modified?