Fedora 40 (XFCE): display power management issue

I installed the Fedora 40 XFCE spin, and display does not blank, after the prescribed period of inactivity.

All F40 updates are installed. In Settings/Power Manager, under “Display” the “Display power management” is enabled, and all the knobs for both “On Battery” and “Plugged In” are set to reasonable values. However, whether plugged in or on battery the display does not blank after the prescribed period of inactivity.

I uninstalled xfce4-screensaver, this made no difference.

Is power-profiles-daemon installed and properly enabled? That’s what fedora uses to perform those actions on GNOME, and from what I can tell reading merge requests it’s compatible with XFCE.