M1 Mac Mini, Displays wont turn on after wake from sleep

I am having the same issue on my new Mac mini M1. Attached to a LG monitor there is no picture when the mini wakes. I have tried using display port cable and thunderbolt. Only fix is to unplug the thunderbolt and plug it back in. I brought the unit into an apple store and they tested all hardware and reinstalled all software. It was not fun to getting it back to how it was and yet the issue was NOT FIXED. This is frustrating and needs to be addressed.

Had this problem with macbook air m1. It seems to me that it worked when I moved the keyboard and mouse to a single direct USB port on the mac (don't use the USB hub on the Dell monitor, nor the USB ports on the USB C / HDMI dongle).

I have a similar problem but a slightly more complicated setup. I have a brand new M1 Mac Mini running OS X 12.0.1 and an older late 2014 Mac Mini running OS X 11.6. These are both connected to a StarTech SV4312DUA KVM switch (along with a ThinkPad Ultra dock and a Linux tower PC). The Mac's both have problems when switching the KVM to them and waking the displays. The New M1 is worst. Windows and Linux work perfectly.

The StarTech has DVI -> HDMI for both screens which are identical.

Old Mac Mini:

• Mini-display port -> DVI on StarTech KVM
• HDMI -> DVI on StarTech KVM
• The behaviour is that the screens either come on correctly and work fine, or the system cycles through a range of possible screen configurations with screens coming on and off and the signal from the Mac coming and going (making the screen report no input) and finally settles into a single config, usually with the correct setup. Sometimes it gets it wrong and gives me just one screen and then relocates all my open windows to that screen (usually a lot of windows across multiple spaces!). This is a huge productivity killer!

New M1 Mac Mini:

• HDMI -> DVI on StarTech KVM
• USB C -> DVI on StarTech KVM
• The behaviour here is more straightforward - it simply doesn't bring up the USB C screen on almost all occasions and relocates all my open windows. Very occasionally it works and brings up both displays where I left off but this is only (and only sometimes) when I have switched the KVM to another machine and switched back before enough time has elapsed for screen-savers or display sleep to activate (though maybe display ports sleep when the screens are switched away).

As I noted above, Windows on the ThinkPad and Linux on a custom-built tower PC both work perfectly (ThinkPad has USB C to the Ultra dock and then Display Port and HDMI to the StarTech KVM; Linux PC has two DVI interfaces direct to the StarTech KVM).

Apple have had a long-standing problem with displays and it looks to me they need to rewrite the display drivers entirely - it's just one bug layered on another as they try to fix this.

Not necessary, disable sleep, be happy.

What works for me - Monitor off after 15 minutes; Computer never sleeps.

The fix is simple - disable sleep.

I have noticed if you sleep your mac mini w/power button and wake it up 5 seconds later works too. That way you don't hafta unplug & plug the cable.

Disabling sleep does not work. I have seen this posted multiple times. I have disabled sleep in an effort to get my LG Widescreen monitor to be awakened by my M1 Mac Mini as well as tried every other way to get this to work and it just flat out doesn't work. Apple has a bug on their hands with this. I would advise against ANYONE buying the new M1 Mac Mini until Apple can address this issue. Any "time saved" by the processing boost of the M1 chip is more than offset by the constant rebooting and plugging-unplugging monitor cables all day just to get your desktop back when you step away for longer than 15 minutes.

Similarly, I have had my M1 Mac mini for 3 days now. I have one Acer monitor connected with a HDMI cable, and one Samsung UHD monitor connected with a Displayport-to-USB-C cable. I wake and sleep the computer 3 or 4 times a day, when I walk away for extended times. This afternoon I woke the computer to one monitor (USB-C) only, the other was black screen only. No open apps were visible on the one screen. Only a reboot of the Mac mini fixed it. And suddenly open apps were on both screens once again, just as a left it a few hours ago. I did not unplug monitors, I just rebooted.

It would appear that this is a monitor waking issue and not a computer waking issue. So right now, I just set "Turn display off after" to never which is certainly far from ideal. At least I have until January 8th to return it! Hopefully, the next OS update will correct the issue.

It would be really nice if Apple would have a known issues list or something but I have to say other than this monitor issue, possibly an issue with getting AirPods to reliably connect, and a periodic crash issue, I would have to say my M1 Mac mini has worked remarkably well. I expected more issues with a new processor along with the normal bugs in a next version OS.

You are not alone. There are several people having big issues with the Mac mini M1 connected to multiple monitors, and so far no solution. There is no response from Apple and nobody could find a configuration that works. Check this post.

https://discussions.apple.com/thread/252072263

Here is a video of what my Mac mini M1 does when I turn it off and on again

https://youtu.be/v1gpgcLzOCY

I have a similar issue. New M1 Mac Mini with 2 Samsung displays (HDMI & USB-C).

Both screens enter a flicker mode after a restart. It also does this after the displays have turned off by the Mini inactivity timeout. I have to disconnect one display from HDMI and restart the Mini. I then reconnect the second screen to HDMI.

My "fix" was to disable the screen saver. I also set the Energy Saver "Tuen off Display" to never. I just avoid restarts.

I also changed my background from slideshow to a single photo that doesn't change.

Another separate issue I discovered while trying to fix this -

The startup keys do not work during restart. Specifically "command R".

I have tried 4 different keyboards and replaced both video cables.

I'll be hoping for an update fix.

Yeah I'm experiencing similar issues with my M1 MacBook Pro. Except it's not when the computer goes to sleep, it's simply when it shuts off the displays. When I tap the keyboard or trackpad, the MBP screen comes back fine but the external display does not. Even disconnecting/reconnecting the display does not help. I have to perform a full reboot. I can consistently duplicate it with both HDMI & DisplayPort. My options are either shut it down every time I'm done with the computer, or disable the system from shutting the display off and rely solely on the screen saver. It does consistently come back with every reboot though. My previous Intel Mac mini had a lot of reliability problems with external display. The frustrating thing is that consistent "it just works" display support is one of the reasons I switched to Mac 18 years ago.

I got my M1 mini a few weeks ago and have a 38 inch LG UW Monitor connected to the USB-C . I haven't encountered any flickering issues but when the computer goes to sleep . There's no display when it wakes up .

I either have to switch to the other USB-C port or HDMI to get the display working.

This did not happen with my 2018 Mac mini.

Turning Sleep OFF does not fix the issue.

Is there a common denominator across the 3 different machines? Such as the same monitor for each? My M1 Mac mini would not wake up with my old monitor but now works perfectly with my new monitor. Same machine, different monitors, problem solved.