Same here - if I (as a pilot) rearm, my operator cannot use pylon mounted weapons (including ATGMs).
If an operator does rearming, he can fire both rockets and ATGMs perfectly fine but I can't.
It doesn't affect the cannon but it does affect targeting - if my operator re-arms, my "CCIP" auto targeting pipper doesn't work for cannon.
It's visible but only really moves when I point the nose at the sky. If I point it at the ground it pretty much follows the main sight no matter the distance to target.