Monterey 12.0.1. Second Monitor Issue

I am having a similar issue on my 2019 16-inch MacBook Pro with 2.6 GHz 6-Core Intel Core i7. When I plug in two external displays to the usb-c ports the OS immediately freezes. Then I have to restart the MB multiple times to get everything to work. I did not have this issue with the previous OS versions.

I have been having similar issues since the Montery upgrade. I have an intel iMac Retina 5k, 27-inch 2020 i7. . The second monitor was challenging to get working after the upgrade. I am using the apple usb-c to vga adapter to connect the second monitor. I have had several episodes since the upgrade where both screens flicker on and off repeatedly. I have found that if I disconnected the vga cable things settle down, then I can reconnect the second monitor. However the environment does not seem stable as I have sent several reports to Apple. This setup worked fine with BigSur for the past year. The only change has been Monterey. Ironically I just went thought an episode after starting to read this post :-)

I have a similar but slightly different issue.

I recently got an imac 2021.

I am connecting an LG ultrawide via HDMI -> thunderbolt cable.

When I turn on my computer, or when it wakes from sleeping it completely stops recognising the LG monitor.

If I go to the system preferences and displays section there is no way to "Detect displays" (holding control does not turn night shift into a different button, nor does going into scaled do the trick).

The only way I can get the monitor to work is by unplugging the cable and plugging it back in twice (from either the monitor or from the thunderbolt, doesn't matter which).

I don't believe it's the cable because before getting this cable I was using an HDMI cable attached to an adapter and was having the same issues (part of the reason I got the HDMI to USB C Cable). I know the adapter is working because I have an External HD hooked up to it, and it constantly recognises that. (Same reason I know the Thunderbolt port is working).

I can hook the monitor up to my old macbook pro (2013) and it works so I don't believe the monitor is the problem here either.

I can still use it, but it means that every time I turn my computer on, or everytime I come back to my computer after locking the screen I also have to go through plug/unplug dance and that's just frustrating.

Just received my new MBP M1max 14 with Monterey 12.0, upgraded to 12.0.1 and tried to use my 32" 4K external monitor via a Belkin TB dock, which I used with an MBP 2018 with Big Sur without any issues to this day. Now with the M1 14 it became a game of chance if the display works properly or not. Sometimes the 32 display shuts down accidentally, seems to fall asleep. Only restarting the Mac helps then. That is not the way I was used to work with my former MBP and this definitely spoils the fun I had with the new machine! Any fix in sight? Besides: the external monitor displays everything a little bit less sharp than before, the overall sharpness was better with the old MBP with AMD GPU :-((

Apple, I've reproduced it twice since we last spoke on the phone. I have three videos and two diagnostic reports to send you, but we keep playing phone tag with each other. Can you please tell me how and where to upload these 300MB files?

Update: I found a reliable but annoying workaround.

1) I login with the laptop screen.

2) When the laptop is booted up and the laptop screen starts to flash every few seconds without lighting up the 38" Dell curved display, I close the laptop lid and go clamshell for a few moments.

3) After about 15 seconds, the Dell 38" display (attached with Apple HDMI to USBC multi-media adapter) lights up, in low resolution.

4) After a few seconds, I open the laptop lid. Most of the time, the 38" Dell display shows the correct primary screen, and the laptop screen has a normal display as well.

I'm in the same boat. After contacting Apple they sent me one of their USB-C to HDMI adaptors and that fixed the problem for a while. Now, my external monitor picture flashes on and off every few seconds.

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.

So having this same issue on my MBP 2019 immediately after upgrading to Monterey. Interestingly - the reason I upgraded to Monterey was because my 2021 MBP was on it's way and I wanted the OS to migrate to the new machine and be jammin' with all the latest and greatest when it arrived and I migrated to the new machine. So for about a week I could not use my second monitor on my 2019 MBP (frustrating). New 2021 Machine arrived about 4 days ago - I migrated using Migration Assistant - and this new 2021 MBP is NOT having any issues with my second monitor. Don't know if that could be helpful info for Apple and not sure the following would either, but the USB-C ports on the 2019 were always finicky - I only had that machine for about 3 months - and during that time I had to buy a new USB-C hub, my previous MBP (now 3 machines ago) didn't have any problems with that hub. The 2019 did. I found the USB-C ports on the 2019 were extremely tight. Like when I would plug that new hub in, it took a little extra pull to get it back out.

I reply to m'y own post to say that i finally made it work.

Using the monitor configuration tools, i set manually the refresh rate to 60hz in the display menu for the usb-c / thunderbolt monitor.

Unfortunately, i did not have to do this with big sur, which seems to detect the rate on it's own.

Those rates are logical, due to usbc capabilities of 60hz max versus 120hz+ for the HDMI. So i can't clame for it. But i can't exp'ain there is no auto détection / configuration for this.

That may help sebody else.

No more problem on my side now.

Nope, it initially worked with Monterey. Then just stopped. My wife's MBP with Catalina connects fine. I have tried every suggestion and it just won't work anymore. Very odd that it did work fine initially (although I had to do the sleep/wake trick once when it didn't automatically connect).

This is killing my productivity.

As a continued update after my call with Apple Support and by now all of us on this thread are aware that Apple is working on a solution, nothing gets my 2nd monitor to be recognized. However, as a last ditch effort to have a useable second screen, I removed my 2nd monitor from my desk and put my iPad in its place. It works wirelessly. Settings > Displays > Add Monitor (toggle at bottom left of window). Click on iPad and voila! While not ideal due to its demure size, it gives me two screens, giving me some of my efficiencies back.

Cannot even begin to describe my frustration. Have been using an external Sony flatscreen TV linked via HDMI to my Macbook using a dongle (since there's only one USB-C port on this Mac) as an external viewing monitor for years. Now with the latest OS update (Monterey) the external screen is black. So now I either have to figure out how to go back to Big Sur or otherwise.... what? New screen? I cant use a new HDMI to USB-C cable since that would take up my only port and preventing the Mac to be connected to power. Suggestions?

Same! This is awful! I just updated to Monterey and now i am not able to use my second monitor as i was able to before the update. I am usingUSB C to HDMI (that works) and i connected my second monitor using USB to VGA not working. Everything worked perfectly before this update. Terrible! APPLE NEEDS TO FIX.

Ditto.

I use my IPad Pro as a second monitor/drawing tablet for illustration work. Upgraded to Monterey. Briefly connects then disconnects. brand new client work and I’m completely dead in the water.

Maybe Santa can fix for Christmas.