It would appear that a unit is unable to take control of a UAV gunner even if they have full control of the drone.
If you place a UAV with an AI entity attached to it on the same side, the UAV operator can access the drone via the terminal, but only has movement controls while the "take gunner controls" is greyed out and unable to be accessed.
However, if you place an empty UAV down (no AI entity), a UAV operator can interact with it and "hack UAV". Once this option is selected, both the gunner and driver controls work as normal.
This is an issue because friendly UAV operators cannot use the gunners on their own UAVs forcing friendly units to "hack" their own UAVs, which is just silly. This also makes it so that only UAV Operators can actually do things with the drone (because of hacking abilities), as opposed to any class with a UAV terminal as it should be.
*NOTE* This appears to only be affecting the fixed wing UAVs. The new helicopter drone (APEX), and the Darter seem to be fine.
Reproduction Mission (VR)