The region does not change it's height with the elevator's height. So the rect's x/y stay the same while the height of the elevator changes, which might effect in seemlingly wrong center coordinates.
So the problem is that there is a visual divergence, because of the different Z coordinate. To fix this you don't have to work with static x/y coordinates of the rect, but instead put them into a formula which also takes the elevator's height into account. You also can try to use approximated values, if it suffices.
Maybe an easier to do, but less straight forward way to go is to use a dummy unit, which also changes it's height together with the elevator. Then you move cam to x/y of this dummy unit, which should have same x/y/z.