Character jump with nav mesh

Hello, im working on an adventure game atm but ive stumbled upon an issue that I cant seem to figure out.
So basically my character moves with the mouse (like in diablo) in order for this to work I use the nav mesh. My problem is that when Im on a ledge and I want to jump it just wont because the nav mesh is blocking my character. I found a way of fixing this by placing invisible objects and messing with their collision settings so that they would cast the nav mesh but wouldnt collide with the player.
This solution though is to time consuming if my level is very large so Im wondering if there is any detail within the nav mesh settings that I can alter so that my character can actually jump of ledges and from one object to another without being blocked.

Thanks