DPMS - Power management does not turn off monitor anymore

It seems a manjaro update (2-3 months ago) made power save for monitor not working anymore.
I have Cinnamon, and never had this problem.
When I set “Turn off the screen when inactive for …” 5 minutes, the screen turns black 2-3 seconds, then wake up again.
I search plenty of help in many forums, manjaro, archlinux, cinnamon, xorg.conf, xset dpms, … nothing works.
I booted with a fresh manjaro cinnamon live usb : after 5 minutes, only screensaver is launching. No power save.
But with a linuxmint cinnamon live usb, it worked as expected : black screen after 5 minutes, then screen wake up only after I moved the mouse.

Any idea ?

assuming you are on X11

query to find your current configuration;

$ xset q

also get;

$ inxi -Gazy


Thanks for you suggestion, but I already tried it, and it doesn’t work …