Sorry, what happens is when you aim the character down, you can see the arm sticking out in front of him. But when you start aiming up, the arm pops out of visibility. It does not move out of camera visibility if that is what you think happens.
you can fix it by turning off “do collision test” of your spring arm but it will effect in other aspects of your game play.
and also by making the length of spring arm shorter so it wont hit your character or ground when you aim up.