I’m having issues with recast graph generation. No matter the settings I change it cannot get it to generate a mesh in certain areas. The layers are correctly set up, but it won’t create triangles in random areas. It leaves large areas around certain objects as unwalkable navmesh. Any ideas what’s wrong or tips to fix this?
More screenshots please.
Attached is a screen shot from the area. As you can see, it boxes out a large area near the one car and passes through the barricade on the right. All of these objects are on the same layer. 
Hi
Reduce the cell size and possibly cell height, it looks like it has a really low resolution.
Check that the barricade is not lower than Max Climb (very likely judging by the distances in the sceenshot).
How large is your world?
It must be kilometers wide with those settings.
The world is about 700 meters by 500 meters. Reducing cell size causes the scanner to run out of memory. Another strange occurrence I have noticed is that if I place a building on the ground, it will mark the inside of the building as a walkable navmesh.
The barricades are 1 meter tall, so the walkable climb should not affect those.
Hi
Try using a tiled graph, that will reduce the memory consumption a lot.
It might actually.
Since the world is voxelized (think minecraft, but with smaller blocks), it might happen that the ground is placed a bit further up because the resolution was small, and the top of the box was rounded down to a value slightly lower than the real one.
Since the y-resolution (cell height) is 0.4, there is a high probability that you will get some rounding errors since the max climb is 0.5 meters.
Try reducing the cell height to at most 0.1.
Reducing the cell height doesn’t increase the CPU or memory, but using a value that is too low can cause it to run out of coordinates if the level is too tall.
I also think you should reduce the Max Edge Error, right now you are telling it that you only care about the navmesh coordaintes plus minus 2 meters, which is a bit much imo.
Try this before you reduce the cell size since reducing the cell size with a max edge error set this high might not even improve the quality of the navmesh.
[EDIT]
Actually, it hasn’t ignored the barricade. You see the triangle slightly upwards and right from the barricade. That is actually a hole in the navmesh caused by the barricade. But the resolution is so low that that triangular hole is what you get.