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.
when you aim down your camera has enough space to stay in its location but when you aim up the camera hits your character’s body or ground and collision option pushes it that you cannot see the arms.
i think you are using an entire character as first person character.
but you can still have “do collision test” on by making the length of your spring arm shorter