Monterey 12.0.1. Second Monitor Issue

Didn't work for me, cant even click on anything because it keeps blanking out both screens.

Doesn't sound like you have been having the same problem as many of us.

You can't move your mouse, you can't select anything.

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.

Update: I can confirm that using VGA > USB-C cable + Apple USB-C to VGA Multiport Adapter, a second monitor works (12.1). The issue seems to be HDMI. It feels pretty good to have the second monitor up and running and not relying on an iPad.

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.

I have tried the same setup with my son's Macbookpro and no problem he connects fine.

So I know it isn't the adapter, tried both VGA and HDMI, it doesn't work, I then uplug from mine and plug in my son's and it is fine.

His is slightly earlier version on Macbook Pro, works fine, I will have to check his GPU when he gets home.

Mine and wife's Macbook Pros same GPU as each other and they don't work.

Same issue here. Apple has shown they do not care for professionals with this absolute negligence.

I’d really like for my $3k laptop to work with an external display; if that’s not too much to ask for.

I updated to macOS 12.1 yesterday and my three external monitors were just fine, but restarting today only one of them would display. I did the restart with Option+R+P keys pressed, and then all three external monitors came to life again.

The QA at Apple has surely been quite lacking with these recent macOS updates.

What a glaring bug from a major vendor.

I just found the same problem. I upgraded to Monterey about 2 weeks ago, and had to connect a second screen today for the first time since upgrading. I used exactly the same set up as usual (same cord, same adaptor and same screen). I started to get the second screen switching in and out, making the second screen function useless. I changed the VGA connection to HDMI and had the same problem. Had absolutely no issues before upgrading to Monterey. How about fixing the bug.

No. that is not a combination listed, and I cannot afford to be trying things that are not part of Apple processes. I did however shutdown and restarted a number of times, and it was not until I had a chance to search the web that I found out that there are a lot of users having the same problem.

Set all high resolution monitors to 30Hertz. Yes, that’s the fix.

System Prefs > Displays

Click on the high res monitor

Click Display Settings

Set Refresh Rate to 30 Hertz

This works on machines with M1 and Intel chip sets. Apple has had plenty of time to address this issue. But Apple never admits to issues without a class action. They might just tell you that your just not using your monitor in the right room, on the right desk, in the right light with the right power source. Sheesh.

I have two offices and at one office I use Samsung 27" curved and dual external monitors work. At my other office I have Lenovo 24" monitors and it only allows me to use one external monitor. Same Thunderbolt dock at both locations.

I just got off the phone with Apple Support and spoke with a man names Cesar. He made me create a new Admin user and see if the new admin user I created could see both my monitors and it could. Some how during the update of 12.1 it corrupted my user but not any new one I could create. He had me login under safe Mode, open the hidden library and go into folders: Cashes, LaunchAgents & Saved Application State. In each folder he had me highlight all files and move to trash. I then logged out of Safe Mode and shut down my MAC, unplugged my external monitors and restarted my mac normally, logging into my normal user. When my mac was up I then plugged in my external monitors and all came up. Like I was before the update. Sorry for this to be so long I have a 2019 MacPro 16".

scrawley1, Apple has had several people call me about this. I deleted all third-party launch agents/daemons from multiple locations, but it didn't help me and my 2019 MacBook Pro 16" with macOS 12.0.1 (and now 12.1). This monitor problem is quite intermittent, so I'm guessing it'll come back to haunt you again. It occurs less frequently if I connect my external screen directly to my Mac with a USB-C cable, bypassing my Caldigit TS3 Plus hub, but it definitely still happens...and infuriates me each and every time.

Did Apple ask you to type the `sudo sysdiagnose` command and upload the 300MB report to them? I did that a couple times. A man named Pedro didn't even thank me for the hours I spent acting as Apple's unpaid QA minion. ☹️

Hey guys,

So I think I figured out what it is. And now that I think about it, I've had this same exact issue happen to me with past updates. After updating to Monterey, I believe my dongle/adapter connecting my monitor to the iMac phased out. Apple does this on purpose - so that you can go buy their adapters. Well low & behold, I went out to best buy and purchased an Apple brand USB-C Digital AV Multiport Adapter where it goes from HDMI in to USB-C out, and this fixed the problem. Not 100% sure it will fix the issue for you all, but it's worth a try. If it doesn't work, simply return it. I am aware that this is a pricey adapter, but this has happened to me in the past with Catalina where they phased out a ton of 3rd party USB docs/adapters. Looks like they did it again.

Nonetheless - this still doesn't solve the known Spotlight search issues on Monterey. The entire OS is bugged, and I restored my Time Machine backup to Big Sur. Seems like these OS updates are getting worse and worse, more problems every year.