Understanding hall-effect sensors and why a motor controller won't work

[Fallingwater]

I have acquired two second-hand electric scooters, one working which we'll call A, and one not working which we'll call B. Note that non-working scooter B has a fascinating variety of mechanical and battery-related issues, but is perfectly able to spin its own motor if a working battery is connected to the power input.

Both come with hall-effect sensors in the motor, but the working one has been modified by the previous owner to work with a sensorless controller. With the hall sensors disconnected and the controller finding the rotor's position on back EMF alone, the motor in scooter A spins perfectly happily.

I don't like this controller, however, because it's a large overpowered e-bike unit that takes a huge amount of space in the scooter's shell and overloads the battery. Since I have the controller from non-working scooter B available and it has a much more reasonable power level, I want to use it in scooter A - but since it doesn't do sensorless mode I have to connect the hall sensors.

However, when I connect B's controller to A's motor, I can't get it to work. If I apply throttle or if I spin the motor by hand *at all* I'll get an E-01 error message on the display, which signals a motor malfunction.

I've opened the motor to have a look-see and found the sensors positioned like the picture in the attachment.

After a fair bit of testing I've developed a suspicion: while metering them I've noticed that while all three change state as I spin the wheel, sometimes all three are high or low. Judging by what I know, this shouldn't be happening - at least one sensor should always be triggered. Indeed if I power up the controller when the sensors are in one of these all-on or all-off states, I get E-01 without having to spin the wheel by hand.

The other scooter's motor never goes all-on or all-off, and I assume this is why the controller is happy with it.

Is there a legitimate hall-effect configuration that allows for all-on and all-off states that the controller I have simply does not understand, or is something wrong in the sensors? If something is wrong, then what could it be? I understand that they usually either short or fail to switch states, which isn't what I'm encountering here.