When creating an addon based on vehicle class and setting isUAV=1, the Action menu entry "Lights On/Off" is missing. However, it is still possible to activate reflectors by using the corresponding inputAction "Headlights" (or by pressing the default Hotkey "L"). The action menu then shows "Lights off".
It seems that this does not affect vehicles based on LandVehicle class. (i.e. UGV) - the action menu entry is visible and functional.
Setup an addon, inherit directly from Helicopter class, add Reflectors, make it an UAV.
Although I didn't do deeper testing, this might also affect other default actions (gear, collision lights, etc.).
Case applies to Stable & DEV Build.
Just an additional note:
Seems like BIS was already aware of this problem and simply disabled the action menu entries. ;)
When entering UAVs on dedicated server, switching lights on (Darter, for example), light starts flickering like a stroboscope... May be an issue with AI again.
Just a quick heads-up: With a recent update (124294) the action menu entry (Lights on) for UGV is also gone. But "Lights Off" is still available when turning on lights via keyboard or command.