Bug in KDE Plasma Power Management

After a fresh installation of KDE Plasma on two devices (PC and Laptop) the Power Management settings are not applied.
The monitor shuts down after about 5 minutes.
KDE Plasma 5.27.10 X11 or Wayland
Power Management → Energy Saving
Screen Energy Saving
Switch off after 20 min
Suspend Session
after 60 min.
The settings are correctly written in powermanagementprofilesrc
Is this a bug in KDE or is the error sitting in front of the PC?