Using PX4 1.7.3 stable.
Turn rover on. It initializes, determines 0 height above aground as expected at the home location. Will navigate various waypoints, but noticed when it goes down hill and the height above ground becomes a negative value and that negative value exceeds the GND_L1_DIST the rover can not "get" to the waypoint. It then drives circles around the waypoint location. Note, if I initialize the rover at the lowest point on the route, everything works fine.
I cannot find a setting to account for this or a way to set (increase to infinity) the waypoint acceptance value for just the z. Increasing the value for the entire radius (x,y,z) is not an option.