How to bake clean NavMesh?

Here are my settings:



Here's what it looks like, as you can see it's not clean, it's breaking:

 

What exactly isn't "clean" about this? The yellow triangles you see? Some of them just look like some mesh renderers poking through the nav mesh visualizer, but that should't affect the navmesh itself.

Is some path blocked that you expect not to be? It's hard to tell from your image which parts you think should be walkable.

 

Maybe you're right, the surface is not exactly flat and thus peeking out, thanks.

 

thanks for the tip.