Grove PIR Sensor v1.2 and Microbit

I have a Grove PIR Sensor 1.2 and I’m trying to use it with my Microbit (v1) and Grove Shield for Microbit v2

from microbit import *

while True:

With the above code, it always displays low/0. I tried another Grove PIR sensor v1.2 and got the same result. To ensure it wasn’t the microbit or grove shield I tried a button and it worked fine.

Any thoughts where I’m going wrong?

Incidentally, I can read_analog - returns values 6 and 986/987