Aqara FP2, mmWave presence detection on WiFi

I got my FP2 yesterday, but at the moment I can’t get it to work. It always detects 2 people in the empty room. I have tried the calibration for noise and it identified the ‘2 people’ and puts squares around them, but still stays the empty room is occupied. My FP1 works OK except it detects people in the cloakroom next to the study.
And, yes I did switch off the FP1 before testing the FP2 so it’s not because they are interfering with each other.
I will try it in a different room later to see if is any better just in case it’s faulty.