Monterey 12.0.1. Second Monitor Issue

I have a brand new 14" MBP and a 27" Cinema Display, connected with a Thunderbolt to USB-C adapter. Yesterday, the monitor worked fine. Today, the MBP won't detect it. I've tried every possible technique in this thread and in other forums. The MBP works fine with my Dell monitor. I tried my wife's earlier MBP (not upgraded to Monterey, thankfully) and the monitor worked fine. This is extremely frustrating and I hope there's a fix ASAP because it's next to impossible to work effectively on just the laptop's screen.

MacOS 12.1 did NOT fix the problem. Still cannot connect external display (DELL UltraSharp U2720Q) using USB-C cable. Changing cables makes no difference. The external display works with HDMI cable but I would expect my 4000 euro Mac to work with USB-C as it did before the update.

Glad some are having success, I have tried HDMi, VGA. Tried the different tricks. Both the laptop and monitors just keep blanking the screen and quickly flashing the display. Can’t move cursor, or click on anything. Even upgraded to the 12.1, still no luck. Sons laptop connects just fine with the same cables so it’s not the cables etc.

Wife’s macbook pro same graphics version as mine same issue. Sons earlier graphic version no problems with same cables etc

Same problem here. Since Monterey I can't use my external monitor. Doesn't matter if I'm using the HDMI/USB-C adapter or the VGA/USB-C one, the result is the same: both screens will flicker on and off like crazy. I was hoping that the minor upgrade from last week would address this issue, but this is not the case.

I read all pages in this thread, followed all tips, but so far there is not a solution working for me, except downgrading to BigSur.

Finally, I tried calling the apple support team, but so far they are insisting that the problem is in my adapter (even though it works perfectly before Monterey). My ticket was escalated to the Engineering Team, and I'm just waiting for now...

Frustration is the best word to describe my experience with Monterey so far.

When I first encounter this issue I called Apple support and they sent me one of their adapters. It seemed to fix the issue for a time, until I plugged in a different monitor and then the problem came back. For the sale of clarity, my computer could always see the monitor, but the monitor reported “no signal” and the screen was blank. After Apple sent me the new adapter, the external monitor would show a picture briefly and then go blank and repeats the cycle. Strangely, today it just started working normally. No idea why as I didn’t change anything at all.

I can say it’s not just related to apple adapters as I’ve tried several different brands. Since most people seem to have started experiencing the problem when they upgraded to Monterey, I suspect it’s a software (not hardware) issue.

I have also been struggling with this issue for more than 1 month!

I have a Xiaomi Mi 34 monitor at home which used to work great before upgrading to macOS Monterey. Now with the 12.1 version the screen connects, I'm able to adjust the settings from the mac display setting, BUT the display is still black...

I have changed the display rate, adjusted resolution, tried a bunch of things like restarted mac completely (with and without the display connected), but still no difference.

This is quite frustrating to be honest and it pretty bad that Apple haven't released any explanation on this issue.

At work, I have a Samsung widescreen and that works perfectly without any issues. I even use the same cable, both at home and work. It's just the monitor at home that causes this issue.

The cable I'm using is a USB-C to Displayport, which supports Ultra HD 4K resolution. And like said earlier, this worked without any issues before upgrading to macOS Monterey!

The plot thickens... I dusted off an old Late 2016 15" MacBook Pro, the first-gen-touch bar model. Installed a fresh copy of Mojave. Same cable, same monitor, no problems.

Upgraded that machine to Monterey 12.2, same cable, same monitor, no problems.

Use the LG app to factory reset it - no problems.

Pull the cable out and plug it into my 16" 2010 M1 Pro MacBook Pro- black screen.

Plug the cable back into the 2016 MacBook Pro - no problems.

I don't suppose anyone from Apple is monitoring this conversation, it would be really nice to hear from you!

I'm in exactly the same place with 12.2.1 as I was with 12.2:

MacBook Pros:

2021 16" M1Pro

(Late) 2016 15"

Displays:

LG UltraFine 5K 27MD5KA-B "X"

LG UltraFine 5K 27MD5KA-B "Y"

(in different locations)

2021 w/ "X": works fine

2016 w/ "X": works fine

2021 w/ "Y": black screen, display not detected, but powers the laptop

2016 w/ "Y": works fine

This is so frustrating. The 2016 laptop's battery is all but shot, so using for anything more than these types of troubleshooting isn't realistic. And I spend roughly half of my work hours at location "X" and half at "Y".

Given that both "X" and "Y" work fine w/ 2016, and 2021 works w/ "X" but not "Y" (new Apple USBC/TB3 cables all around), I still have to believe that there is some firmware or software problem at work here with my new laptop... perhaps something stupid like "The M1 software driver/software stack can't handle different instances of the same hardware model display"?

My LG 5k monitor couldn't reply the M1 Pro screen since the last update of Monterrey. While the Macbook pro M1 was installing the screen monitor turned off and until now my monitor works. I ’ve taken it to technical service and the diagnosis is burned power supply board.

Apple isn't transparent, nor have they tried to solve anything and is hidden solutions.

Has 12.3.1 fixed the External Display issue for anyone...?

It seems that Apple has acknowledged the issue by virtue of putting out a fix... for some of us, but unfortunately not for me. If you are a Mac Mini (2018) owner, seems your problem may have been resolved. Even though I am on a MacBook Pro, I had hoped that there would be a chance this fix would resolve for all platforms.... unfortunately not the case.

This update [12.3.1] fixes the following issues:

- USB-C or Thunderbolt external display does not turn on when connected to Mac mini (2018) as a second display

- Bluetooth devices, such as game controllers, may disconnect from your Mac after playing audio through some Beats headphones

I am still faced with a situation where the MacBook is aware of the External Display being connected, but does not put out a signal to it. Anyone want to place bets on when(if) Apple will put out a general fix for all platforms..?!?

I still have the issue with 12.3.1, what the **** Apple!!!!!

MacBook Pro 2016 connecting via USB C via adapter Minidisplay port to Apple Cinema Display.

It has always worked with no issues until I upgraded to MacOs 12.

Some times I can make it work by powering off the display and powering on but is a hit or miss. There are days that I can use this trick and then other days that it just won work.

Describing the problem:

1- The MacBook Pro detects the screen as it arranges the desktops as if normal

2- but the Cinema Display is just black.

3- Some times the screen flickers at the very beginning of connecting with the MacBook Pro like it wants to show the image but goes immediately back to black.

4- Some times the screen works by powering it off and on.

This is ridiculous. Apple should have a bug fix for this by now. I can’t imagine that many people who work exclusively on Mac’s DON’T have at least one external monitor.

I got on a support call with Apple and my problem is resolved

I got on a support call with Apple. Got a senior tech person. Issue resolved