if it was Hydro it should loose drive both directions.
no code would mean controller is not seeing an input - fault in directional lever or wire circuit to the controller.
Remotely possible that one hydro pump has a directional/check stuck open so that motor does not turn and with axle matching flow to the other motor is shut off. To test for this refer to the operation manual and turn "Axle Matching" OFF, if check valve is stuck open it will drive on one axle.