Aborts usually occur as a result of obstructed geometry. What constitutes obstructed geometry can sometimes be surprising.
I had this problem on a project where it appeared everything was working okay, but the level’s geometry had been imported as a single static mesh. Its collision was automatically set to one solid collider hull built around the whole level. Funnily, this does not prevent a nav mesh from being generated inside of it, and so everthing can look perfectly okay even though all the actors are living inside solid collision. By getting rid of this collider completely, we successfully enabled AI to navigate the level.
That’s what I’d advise looking at first – in your viewport, click “Show” and then check “Collision” to see how that actually looks as compared to the expected layout of objects in your scene.