Perhaps the connector on that particular 3-Wire Extension is bad. It could be an intermittent disconnect, short, or even some kind of corrosion in the extension that causes the pot values to appear to jump around. If you have an ohmmeter, you might try testing the cable to see if it shows problems when wiggling it around.
It was something to do with the wire I believe. I’m gonna try and replace it soon and post the results back on here. I’ve heard of Sensor values and such being off because of broken tech but never have I had problems with wires causing off values.
The problem could also be where the 3-wire cable is wired. If they are wiring right next to or with motor wires, the value will be very low, and when you move the potentiometer the value jumps up and back down.