I just tried it now (nearly forgot it after downloading a few weeks ago), but I don't know how to execute the pathfinding. the blocking tile placement/removqal is fine, and the start/end point placement too.

I started to deal with navmesh pathfinder again in Unreal Engine 4, but I find it not really suitable for a complex RTS game, because it is difficult to handle different sized agents avoiding collisions, and agents with different capabilities (ladder climbing, slope, swimming etc.). in my custom pathfinder each capability requires its own base map, but agent size handling is easy. in UE4 you can also place blocking volumes, they said to work fast runtime too, but not tested yet.