I’m having the same issue. Should the screensaver be off? I did the original config;

sudo nano /etc/xdg/lxsession/LXDE/autostart

add the following lines:

@xset s noblank
@xset s off
@xset -dpms

sudo nano /etc/lightdm/lightdm.conf

add the following lines:

xserver-command=X -s 0 -dpms

but the screen was still blanking after 10-15 minutes so I installed xscreensaver to get around this. I’ve now taken xscreensaver off, so the screen is blanking after inactivity again, but MM doesn’t seem to recognize the PIR. I get the same results of ‘Motion Detected’ when running a .py test from the OS.