screensaver no longer starts

Hello William M.,

Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with your screensaver. Next, what we would recommend, is testing this issue in another user account. What we need to do, is log out of your current user. Log back in under another Standard or Administrator account and see if the same issue occurs there. This way we can tell if it is an issue with your user account, or if it is system wide: Set up users, guests, and groups on Mac - Apple Support

If it occurs there, try starting up in safe mode to see if that resolves the issue: Start up your Mac in safe mode - Apple Support

"Start up your Mac with Apple silicon in safe mode

1. On your Mac, choose Apple menu  > Shut Down.
2. Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.
3. Press and hold the power button on your Mac until “Loading startup options” appears.
4. Select a volume.
5. Press and hold the Shift key, then click Continue in Safe Mode.
6. The computer restarts automatically. When the login window appears, you should see “Safe Boot” in the menu bar.

Start up your Intel-based Mac in safe mode

1. Turn on or restart your Mac, then immediately press and hold the Shift key until you see the login window.
2. Log in to your Mac.
3. You might be asked to log in again.
4. On either the first or second login window, you should see “Safe Boot” in the menu bar.

Verify your Mac started up in safe mode

If you’re unsure whether your Mac started up in safe mode, you can use the System Information app to check the mode.

1. On your Mac, choose Apple menu  > About This Mac.
2. Click System Report.
3. In the System Information app, select Software in the sidebar.
4. In the System Software Overview, look at the value listed next to the item labeled Boot Mode.

• Safe: The Mac is using safe mode.
• Normal: The Mac is not using safe mode."

We hope this helps.

Cheers!

You are not alone, I've got a 2019 retina iMac (Intel) and the latest update broke both screensaver and monitor sleep, neither work at all now and it just stays awake...is system wide since it happens with another logged in user too. Multiple restarts and resets haven't resolved it I'm just waiting for the next update to fix it hopefully.