After wasting two hours trying to fix up what the recast generator made, I tried Havok... the whole landscape was cleanly tiled, and the ruined inn was made of only four islands, fitting the obstacles like a glove. Merge a handful of nodes on the island borders, and done - the whole cell fills green.

Bumping this since mods locked the other thread about getting better results from automatic navmesh generation. (This is not about "The Navmesh Bug". It's about using the CK to better effect.)

As an addendum to the first post, I did run into some problems where Havok extended the navmesh through pillars where NPCs would get stuck, but fixing it was just a matter of plopping down a few new nodes. Much easier than hand building where recast generation refused to extend navmesh anywhere in the vicinity of the pillars. Or half the landscape.

Setting "overlap distance" in the Havok dialog to 256.0 seems to produce cleaner results as well. I'm not sure why this is, but it seems to be a somewhat magic number, as 128 and 300 resembled each other more than either of them resembled 256.

Could you go over how to do it via Havok? I am unfamiliar with this and might need to start nav meshing my cell soon.

Under the navmesh>Generation menu, instead of choosing Recast, just choose Havok.