2D-Animation - Character snaps away?

Hey guys!
I tried to come up with a simple animation but I am having a strange issue at the moment.
Whenever I try to animate my character in any way (no matter if I try to move or scale a certain part) it just completely snaps out of the screen and messes up all of the transform's settings.
I hope you can detect my problem while watching the footage I recorded.

Thanks in advance!

 

Addition: The transform position sets itself to enormous high coordinates. So whenever I create keyframes using the record mode they position-keyframes which get generated at the very start have such high coordinates. (up to 4*10^4)
Does anybody have a solution or even seen something like that before?

 

I don't do 2D so I might be totally off here, but I think this thread might be relevant.