AI fall off navmesh, What are your work arounds

The navmesh does not cover ALL of the ground because of the radius of the actor you set. Sometimes my AI gets knocked off of the navmesh. What are peoples way of dealing this??

I was trying to do a raytrace down to see if the character is no longer on the navmesh, But It always returns true. And when my actor jumps and lands on the ledge of a box, he freezes there without any navmesh, and it fails with BLOCKED, instead of Off Path.

Bump on this also!

Yeah, Im Making A 2.5d Game, Where The Area Of Movement Is Limited, When They Move Off, They Just Repeat Attack lol