Clevo P870DM > DPMS not working

I have a Clevo P870DM (also known as Eurocom SKY X9E) and the DPMS Suspend/StandBy/Off doesn’t work. Screen goes black but backlight stays on.

I have tried everything I could think of.

Backlight can be controlled with xbacklight.

Attached is the edid.txt.
edid.txt (384 Bytes)