Two issues so far:
One is that the quadcopters will not land using the UAV terminal, they seem to be baffled by the concept of landing and tend to fly straight back up and jerk around.
Second is that the UAV drones (planes) turn the autopilot on randomly sometimes when you give the UAV commands through the UAV terminal. I know this because when you then take control when the drone is meant to be going to the waypoint the auto landing scroll option is on.
This can be tricky as this happens randomly, but generally placing waypoints will make the plane auto land.
As with the quadcopters, simply commanding it to land via the UAV terminal will cause it to play up.
EDIT: The plane auto lands when the support type is used, this for some reason makes them land every time they are left on their own, even after you disconnect from them and reconnect.
This issue is still persisting (the Greyhawk always wanting to land when releasing controls), it is a real pain, especially since there is no known way to fix it, when it happens say good bye to your UAV, even if you let it land as soon as you get back in the air it will land itself again. I also ran into a similar issue where by the Greyhawk just started flying north every time I released the controls, despite any waypoints i placed. I believe it also stemmed from mucking with advanced waypoint controls.
I am surprised these are still issues well over 12 months after being reported.