Tunguska Locking in Third Person Using Radar?

When I’m in third person and use the radar circle to lock stuff - the radar never locks high flying objects. It seems that even though the search radar will see the object, the lock “rectangle” is always in line with the ground.

Am I missing something here? Often, my radar will see the enemy before I can see him visually, however if he is above this rectangle, I will never get a lock. I have to go into first person mode, visually aquire him and then lock that way.

Can anytone tell me if this is expected behavior, a bug, or am I missing some control input?

I should add, that the radar will make an attempt to lock, and accurately moves the lock horizontally, but does not move it vertically to match the target.