Dragging 3d object vertical doesn't work

Hi!

 I've followed this example but when I drag the object up/down the scale changes. But if move it left/right it gets dragged.

 I would expect that you would have to pinch for the scale to change. But apparently moving up vertically changes the scale.

  https://lensstudio.snapchat.com/guides/scripting/manipulation/

 Actually it looks like even moving it horizontally changes scale...

 Could you provide an example like this where the scale change only occurs if the user uses two fingers? (pinch gesture)

thanks