I agree with all. It should like interference from some other bluetooth device perhaps even the puck. Ensure all BT devices other than the Ultrex are off and then try turning the puck on and see if it freezes. If not turn on another ETC.
I suspect you have a bad puck and it is sending mixed signals to the Ultrex.
AS stated above it you do not use the jog feature then just keep the puck off, but I would be trying to find the culprit.
Also as suggested make you you have the latest firmware update.