Having a UAV operator drop the UAV and take control is fine when he is alone (spawned in editor), but when you link them to a group they can no longer (Connect terminal to UAV) - menu item doesnt show.. Unlinking the UAV operator fixes it.
Pretty sure its a bug, unless the higher ranking squad members have to control it, but it wouldnt make sense as the UAV operator has the controls.
Video Attached - to replicate - It was in my mission, but same thing if you do it in a blank mission