M1 Mac Mini with LG 5k External Monitor Issues

Does the display come back on when you move the mouse (it should). If it does then perhaps it is an issue with your keyboard. I have the same setup and no issue coming back from sleep (although it take a few seconds). If you set to "turn display off never" in the energy saver pane it should stay on. Just use a screen saver instead.

Good move to check "Prevent your Mac from Automatically sleeping"

I would also uncheck "Put hard disk to sleep" and Wake for network access" and test computer Sleep from the Apple dropdown Menu. I say that because my Mac Mini running Monterey has no issue Sleeping when manually put to sleep. The only difference from earlier macOS versions is that it take two clicks, one to wake the computer and one to wake the displays.

My displays are on the Auto sleep timer and always sleep/wake as expected.

I was referring to Computer Sleep from the dropdown menu which works just fine for me.

(I have no problems with crashing and no problems waking the computer)

True. Sure it does, because it also puts my external drives to sleep. Plus I would rather sleep/wake my Mac than continually have to start it up.

EDIT: Basically I'm just offering up another work-around for eagle442 and others to test.

“sleep/wake my Mac than continually have to start it up”

??? If it’s not sleeping, a tap is all you need to bring the display alive. As for external drives, depending on which one, they usually come with (configurable) built-in sleep functionality. When not in use, drives consume negligible power anyway.

The point is, flawless manual sleep is not a universal solution/workaround for wake-from-sleep issues. It’s very much config and peripheral-specific, and even then has limited benefit.

Uncheck “Put” and “Wake” for completeness…and yes, that should permanently fix it.

You've tried the Mac Mini's other USB-C port?

You've tried using a different USB-C/Thunderbolt 3 cable?

https://www.apple.com/shop/product/MQ4H2AM/A/thunderbolt-3-usb%E2%80%91c-cable-08-m

Could you post a snapshot of your Energy Preferences please?

Manual sleeping is unnecessary dear den.thed, let the timer do it for you 😉 (or just turn the monitor off if you’re concerned about privacy).

I was too. The crashes are related to individual configurations so what works for you may not for others. That said, you also don’t need to manual-sleep…it doesn’t get you anything…