I read up on the board, and it seems to be an exceptionally soft board. If you are doing turn initiation with your front foot but never bringing up the rear foot to match, you'd be trying to turn with an edged front and flat back. That'll wash you out for sure! If the rental board is stiffer, your front-foot initiation is probably enough to bring the edge up in the back as well.
So, do you just have a lazy back foot?
That and, correct me if I'm wrong, but wouldn't a flat or zero camber board behave differently in turn initiation that a camber profile? I recall when switching from camber to C2BTX I had to adjust (dial it back) otherwise I would wash out.