Character gets stuck attempting to use a Navlink

What would cause a character to get stuck attempting to use a navlink (To drop down off of a ledge onto the ground)?

The character paths over to it, then teeters back and forth right on the edge, never actually taking the plunge.

Unless I missed a checkbox somewhere they should be fully capable of both walking off of ledges, and jumping.
As near as I can tell the link is valid, it shows as a green arc when the navmesh is displayed.