Monitor not waking from sleep after 12.3 upgrade

Apple support has not been able to fix this for me. I have exhausted their suggestions so far. Let's do a simple summary recap of what I have tried at Apple's suggestion or on my own from threads I've read:

• Reset SMS (Mini - long hold power for 10 seconds, let go, press power again to restart)
• Reset PRAM / NVRAM (From Mini off, power on after chime holding [CMD]+[OPT]+[P]+[R])
• Turn off Sleep Settings.
• Download Monitor Drivers (if any) from manufacturer. (There were none for Mac).
• Reinstall Mac OS 12.3 from Recovery Mode (From Mini off, power on after chime holding [CMD]+[OPT]+[R]).
• Try combinations of plugging & unplugging monitor power/connection cables.
• Tried on my own using HDMI in addition to USBC cables and it worked ONCE immediately. Being suspicious I restarted from Menu and no go thereafter no matter what I've tried. I also tried using only HDMI & USBC-HDMI cable config and no-go.

NOTE: For Mac Book users with same issue, you would also have to include turning off SLEEP & graphics card settings as mentioned in this and other threads. I am on a desktop and don't have the same issue as I am always on power, but I did disable all the sleep settings just in case they were the problem. They don't appear to be the problem with desktops.

Some responding messages claim this is an LG only issue, it is clearly not from this and other threads AS WELL AS MY OWN EXPERIENCE of swapping late model 2021 LG monitors with late model 2021 Samsung Monitors to no avail. Both sets of monitors worked fine as individual monitors on 12.3, but NOT when connected as dual monitors. Both sets of monitors also work fine in Mac mini running 12.1 as DUAL MONITORS.

Meanwhile, My identical Mac-Mini 2018 running 12.1 happily shows both sets of monitors that are not working on 12.3 (Samsung and LG). No flicker, in 4k, sharp/clear text, no stagger/blur motion. Connect said monitors to Mac-Mini 2018 running 12.3, left (second monitor for me) monitor is blank and floating USB-C No connection text is floating around telling you monitor is powered, but no signal.

For those of us who are developers, we can't simply ignore this and downgrade as we need the latest Xcode and its' support for iOS 15.4 and the fixes and implementations it contains, not to mention configuration compatibility with others on teams. Therefore, it's quite a predicament to be in.

The B _ _ _ word for testing seems to get Moderator editing. so I will state that I not only had this issue with 12.3 while it was in 'B-testing' (as most developers download them as soon as they are available for Xcode fixes and compatibility which many times come hand in hand not to mention Xcode supporting apps (Symbols, Instruments, etc.)). I also reported it on both the B-Testing expected path and in the critical/system is down path of phone support. The first method has never been commented back on by Apple. The second, after 30-minutes+ of escalation, the highest escalation simply said "That's B-Testing software and we do not support it, that's why its called B-Testing".

Not what I wanted to hear, but OK, fair enough. So I spent about 5-hours the next day rolling my system back to a clean install of 12.1 public release. So this has been a known issue for Apple, from my own submissions as well as others, for many weeks now and obviously not fixed in the final version.

With nothing else to try, I ordered 2x$25 each top of the line Thunderbolt 4 and USBC 3/4 cables to see if they make any difference. Cables expected to be delivered tomorrow and I will post if they make any difference.

-Kevin.

I can also confirm the issue on my Mac mini i7 2018. The problem would appear to be some sort of driver issue introduced with 12.3. On my Mac:

1. When waking from sleep, the monitor wakes and seems to receive a signal but is entirely black.
2. If I wake from sleep, get the black screen and do a restart without shutting down via VNC or ARD, the monitor goes to standby and receives no signal.
3. If I boot my Mac headless and thereafter plugin the TB cable, the monitor receives no signal and remains in standby.
4. Only shutting down and initiating a full boot sequence with the monitor plugged in will result in obtaining a proper video signal.

Disable Sleep, it’s unnecessary on later Macs, all pain, no gain. To disable, set your Energy Saver settings to as shown:

Separately, avoid manual sleep, use screen lock instead or let the display switch off/auto-lock on timer. For long or overnight absences, shut.

I'm sorry, but did you infer I am making this up for some bizarre troll reason? I have attached the Samsung model plate of the monitor(s) in question. This is NOT specifically an LG issue regardless of your interpretation, as there is plenty evidence in general that it is happening to other brands also. I swapped out a non working pair of LG's to a non-working pair of Samsung's and you have the audacity to question the validity of my statement? I have better things to do as a 39+ year developer, 10-software patents holder and full time iOS developer since iOS 3.2 than to 'troll' tech boards with fake claims. You have one heck of a lot of nerve responding to a user with such a response.

Attached is the model info from the NOW Samsung pair of monitors attached to my Mac mini 2018 running 12.3 that the monitors work fine on my Mac mini 2018 running 12.1 in other office.

Spoke with Apple support last night, other than SMS, NVRAM & PRAM reset standard bits, they ultimately escalated to a senior and after about 15 minutes hold time came back and said they are aware of growing issues with users on this subject and to try recovery mode reinstallation of Mac OS 12.3. I will report back if reinstallation helped. Obviously this will be a multi-hour initiative.

-Kevin.

[Edited by Moderator]

Exact same issue - never had this problem before. My Mac is set to not sleep and the display is set to turn off after 15 minutes, when the display wakes up it goes black and turns off again almost immediately because it's not receiving any input from the Mac.

Only way to recover is to power off the Mac.

Same issue for me. LG 27UL850-W. usb-c connection to monitor seems to have this behavior every time after sleep. Tried HDMI, which doesn't happen every time it wakes, but still does fail. Also, once while trying to unplug/plug in the HDMI and usb-c cables to correct it without turning the mini off, the mini restarted itself with a kernel panic.

Only started happening with 12.3 update. No issues at all prior to the update. And it started immediately after the update (I was using a different input on the monitor while the update was running and had to hard restart it when I went to get back into the computer after the update completed).

I have a new ASUS monitor coming tomorrow (had on order prior to the 12.3 update), so I'll see how that one does.

It’s monitor dependent, LGs appear to be the most vulnerable. Do you have a discussion link to your issue posted here? If not, feel free to start one. There could be other fixes you haven’t tried yet.

I had swapped out my LG’s with pair of Samsung tonight from another Mac still on 12.1, same issue. I had this issue and reported it when it was in 12.3 was in Beta to deaf ears at Apple. I had to downgrade and revert back to public release at that time of 12.2. A seven hour process to restore system and files. I read from some other devs at the time that they thought it was related to the new feature for Universal behind the scenes and more affected larger format displays. Having only ultra-wides here, I couldn’t test on standard sized monitors.

I’m sorry but seems to me that you’re adding Samsung to this problem on-the-fly when in fact your issue is with LG. Samsungs may well have issues too but as of now I haven’t seen an original, credible discussion mentioning them in the first instance as having this issue.

In any case, confirmation that LGs have the problem is enough. It’s either a newly-introduced bug or newly-introduced fix to a long-standing security hole for 3rd monitors that aren’t fully compliant with Apple’s requirement for unique ID.

Only time will tell, all the best.

Just because YOU haven’t seen any discussions about other monitor brands, doesn’t mean they don’t exist:

https://forums.macrumors.com/threads/no-more-extended-2nd-monitor-after-12-3-update.2337966/post-30935459

https://forums.macrumors.com/threads/monterey-12-3-beta-broke-second-display.2332775/post-30938696

https://forums.macrumors.com/threads/monterey-12-3-beta-broke-second-display.2332775/post-30937616

And who decides when a discussion is "original" and "credible"?

I wrote “seems to me” = IMO = in my opinion. I stand by it, not interested in macrumors. In case you didn’t know, a rumor is neither original nor credible https://www.merriam-webster.com/dictionary/rumor…thanks anyways 😁

I wrote “seems to me” = IMO = in my opinion

No, you didn't.

"but as of now I haven’t seen an original, credible discussion mentioning them in the first instance as having this issue."

Instead of losing yourself in pointless semantics discussions, you could try to be helpful. Or silent.

If you discredit user experiences, just because the forum they posted them in is hosted by a website with "rumor" in its name, you appear to be biased and driven by your own agenda. Let me guess, you wouldn't believe something by 9to5mac either, because you're not interested in normal business hours.

You seem very determined to lay the blame solely at LG's feet and acquit Apple from any wrongdoing, when other brands are also concerned and all these monitors worked fine before 12.3.

Which post are you referring to? Mine was to my last response to DVMagicStudios after which you jumped in. It’s there in the very first sentence. And yes, I’m only responding to user experiences on this site. Based on it, only LGs are exhibiting this issue because their implementation is suspect. Links from other discussion forums/I heard it on the internet…hmm, maybe silence is the best answer 😁

hcsitas wrote:

Which post are you referring to? Mine was to my last response to DVMagicStudios after which you jumped in. It’s there in the very first sentence. And yes, I’m only responding to user experiences on this site. Based on it, only LGs are exhibiting this issue because their implementation is suspect. Links from other discussion forums/I heard it on the internet…hmm, maybe silence is the best answer 😁

Just not true. You responded to a post clearly stating that Samsungs are affected, too.

DVMagicStudios wrote:

I had swapped out my LG’s with pair of Samsung tonight from another Mac still on 12.1, same issue.

hcsitas wrote:

I’m sorry but seems to me that you’re adding Samsung to this problem on-the-fly when in fact your issue is with LG. Samsungs may well have issues too but as of now I haven’t seen an original, credible discussion mentioning them in the first instance as having this issue.

I do understand your frustration, but there’s nothing in your reply it that contradicts my post or gives me pause. So, it stands as written including this bit: “All the best.” I hope you and others find a resolution soon. Good luck! Keep us posted.