Which magnetic sensor are you using? I2c or spi? How confident are you that the sensor reading is being read properly?
What i like to do is to start with ‘voltage mode’ and set voltage to zero (with motor.move(0) and then call motor.monitor() straight after. It’ll print out “voltage angle velocity” with each loop. Then manually rotate motor 360degees. I’d then expect to see angle (second column) to change to 2*PI. If it doesn’t then go back and look at your sensor setup. If it does then continue in voltage mode changing values in motor.move() from -2v to +2v and see if motor turns in both directions. The advantage of voltage mode is that it doesn’t use PI tuning so is easier to debug hardware/connection issues.
If all that works then it’s a problem with your tuning