Controller goes full speed past a certain throttle voltage

I have a 48V Lyen 9 FET controller that I connected to a Bafang BPM2 hub motor. Currently, it has some unintended behavior. When I push the throttle past a certain point, the controller spins the motor all the way up to full speed, and does not stop spinning at full speed until I move the throttle back to the point of 0 throttle. I also tried testing with a multimeter connected to a potentiometer knob and breadboard that I had, and it gave the same problem. With the multimeter, I saw that the motor starts spinning once throttle signal is 1.3V, and I can control the speed just fine until the throttle signal reaches 2.3V. Right below 2.3V it is not spinning at maximum speed. Right at 2.3V, the motor jumps all the way to full speed. Also, being around 2.26V causes the motor to alternate and pulse between maintaining its current speed and spinning up to full speed. Bringing the throttle signal below 2.3V does not change the speed until I go below 1.3V, when the motor stops spinning entirely. What might be causing this behavior, and how can I fix it?

do you have a photo of your controller