Ge has a limit to how far you can fall, it will somtimes reset itself if the view is fallowing the falling object(it did for me in Game mode)
but when you have an actor that moves to your player constantly(the falling one) it will start going up after a while of the player falling...
(the faster the player falls the quicker.)
I just felt like posting this hilarious error(it looks funny in my Game in Game Mode in GE(And out of it! )! )