I have just finished building an Emax babyhawk using the Rakon frame (which is very nice) but it oscillates really bad on the yaw axis. I have tried re flashing both the FC(Femto f3) and the ESC's with various firmware versions, all of which fly perfectly well on all axis apart from yaw,i have soft mounted the motors but there is no option to soft mount the FC, this helped a bit but it's still doing it. When i look at the graphs in betaflight motors tabs(with the props off of course)i can run the motors up to full speed and see hardly any vibrations. I have lowered P and I on the yaw, and can get it to fly rock solid ,now this is where it gets weird.No matter how smooth and locked in i get it, this all goes out the window when i put another battery pack in then i'm back to square one with it twitching like mad. I've built several of these babyhawks both in normal X configuration and 2 in plus configuration and have never had this issue. Could it be that i've just had bad luck and got a bad FC with a dodgy gyro or something else? Please help as this is really driving me nuts!!