Windows 11 Screensaver / Display Sleep functions not working

Ditto and ditto. I give up. So, I tried a couple of Mac OS "hot corners" type apps for Win, and this one works fine with Win 10 and Win 11: WinXCorners — Hot Corners for Windows 10 https://apps.codigobit.info/2021/07/winxcorners-hot-corners-for-windows-10.html And, it's free. There's no timer on it, so you have to manually move the mouse to a corner to start the SS. But, since the chances of MS fixing this are nill, it's better than nothing. <- That sounded like a snark against "WinXCorners" but wasn't meant to be: that is a wonderful program and thanks for making it winxcorners people. Okay bye now.

No kidding. Re-installing using this method ended up corrupting my files and I lost everything. And now there's been no further response from MSFT in months about this despite more people having the issue.

I have this same issue. Works after reboot, but then just stops and never re-engages. I tried every suggestion in this thread, and none of them resolve the problem.

Following up: I was able to fix the issue on my end. This may NOT work for everybody, but for me it came down specifically to SSD firmware. Maybe it'll help somebody figure out their issues?

TL;DR - My SSDs had out of date firmware. Updated the firmware, all problems fixed. Somehow.
SSD Model: Western Digital SN 850 NVMe

In Depth:

My system had two specific issues:

1. Monitor power savings mode would never reliably engage.
2. Every once in a while all the icons on my desktop would blink a few times, but no errors/problems otherwise. Thought it was a visual glitch in Windows 11.

However, when checking event viewer I was getting a repeating system error.

Lists a device name of PCI\VEN_8086&DEV_7AC8 as the culprit (this is a random PCI-E port name). Thought this may be a motherboard error for a while, and tried every driver version possible. As a last ditch effort, I disabled the PCI-E root port in Device Manager juuuuust to see what happened. Turns out the port was tied to one of my NVMe drives. Decided to download Western Digital's Dashboard app to see if I was getting SMART errors or... something. Didn't know what to expect. No errors, but it flagged both my drives as having out-of-date firmware.

Updated the firmware... and holy carp, both issues resolved. Power savings now works reliably 100% of the time, both monitors go into standby, AND the weird icon blinking issue stopped completely.

Again, this may not work for everybody, but I've also never seen an SSD's firmware stop a monitor from doing its thing. So... I guess if nothing else has possibly worked, and even if you're not getting an error like the above, check and see if your SSD firmware is out of date. This may be a weird needle in a haystack solution, but it worked for me, maybe it'll help somebody else out.

For ref: the original firmware on the drives was from when I bought the drives back in December 25, 2020. I don't have the original version number, but they hadn't been updated since I bought them.

I have this same issue. Works after reboot, but then just stops and never re-engages. I tried every suggestion in this thread, and none of them resolve the problem.

Did not solve the problem permanently.