Custom navmesh, increasing polycount?

[Graylord]

So I am having an issue with a custom navmesh I have.

There's a large flat area in my level, so in my navmesh model I have made crossections of polies to increase the amount of points the pathfinding can use (as it appears to only use the center of each navmesh poly).
But when converting it to a navmesh UDK merges those faces together, (setting different smoothing groups doesn't work) how can I force it not to do that?

[Graylord]

I can tell from the wireframe that the shape is as intended on import, it happens when it's converted to navmesh.