MicroBit Light meter: Kitronik Move Motor issue

If we set up a simple light meter using a standalone micro:bit we get light reading X
If we then put the same micro:bit into the Kitronik moveMotor we get light reading Y,
Y is always much higher than X
We cannot work out why? any ideas

The Micro:Bit uses some of the LEDs in the LED matrix as light sensors, basically just by switching them from outputs to inputs from time to time and measuring the voltage decay time.
Perhaps the voltage form the Kitronik Move Motor interferes with these measurements?