XPS 8960, will not blank S3221QS and thus will not sleep automatically based on power settings

Hi:

I have had this machine for almost two years and in general am very happy with it.  However, Sleep has always been a persistent pain.

While it is possible to configure the machine to sleep via the power button and via a third-party Desktop Shortcut, doing it based on the Power Settings automatically does not work.  And then if there is an update in the middle of the night and it wakes, then it will not go back to sleep.  For a long time it was OK and then stopped working.

I finally determined that just having the display plugged in to the PC regardless of whether the Dell-S3221QS display is powered on will prevent the display from staying blanked, and thus preventing Sleep.

So the issue is really blanking the display.  If, for example, Power Settings are: "Turn off Display" set at 1 minute and "Sleep" set at 2 minutes, the display will blank for around a second every minute and then come back on, but never sleep.

So I've resorted to Hibernate but that is less desirable.

This is a fairly standard setup with 32GB, several SSDs, one HDD, the Nvidia Geoforce RTX 4070, Windows 11 Pro.  Windows and drivers are up to date.

Thanks for any suggestions.  My apologies if this has been covered.

---- sam