Monterey 12.0.1. Second Monitor Issue

So I have two Dell 27in 4K monitors running through a Cal digit element hub with a single thunderbolt 4 cord going to the 2021 16” MBP clam shelled.

A temporary workaround that worked for me was to increase each display scale to a higher resolution. Once I did that the screens both stop flashing. It is still not picking up hdr on either monitor but at least it stopped flashing.

With that problem temporarily fixed, every so often I the second monitor starts flashing. I just change the display scale a few times and it works.

Obviously this needs to be fixed but I hope these temporary solutions work for you.

I was able to get this to work on my mac mini by doing the following:

• Power down CPU
• Unplug thunderbolt monitor from Mac Mini
• Power up CPU
• Once you have an image and are logged on - connect the Thunderbolt monitor

I have powered down unsuccessfully, I lose the settings. But, as long as I keep the machine on - it works.

I hope this helps, this bug drove me mad for a few hours.

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 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".

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.

2 Weeks ago, I had the same issue, second monitor, a hardware color-calibrated NEC Spectra View 32 display, which was connected to an MBP M1max via a Belkin TB 3 dock, only showed a slightly shimmering shine, noting else, when I raised the MBP out of the sleep mode. In my case, it was the ICC-Profile. It was a Basiccolor display software generated LUT Profile, which caused this. After changing the profile to a Matrix-Profile, it worked again. The update to 12.1 seems to fix the LUT-Profile problem. Now the display works with both kinds of profiles, LUT and Matrix, as it did with the former MBP 2018 under Big Sur. Apple Support was rather surprised about that, but: it works for me.

I had the same issue running a Dell monitor. I was able to go into Security & Privacy / Privacy and select "Screen Recording" which I had to allow multiple apps to "record contents of your screen...". Shut down the apps and re-opened and POOF the Dell monitor came to life.

I have an iMac 24" 2021 M1 and the second monitor worked for a while. In the beginning, it would reawaken with the iMac, but gradually, it would not awaken and I had to use the power button to turn it back on. Eventually, it ended up needing unplugged and plugged back into the iMac. I think I updated to 12.0.1 and then it wouldn't be recognized at all. So, I unplugged it from a regular Thunderbolt (C) port and plugged it into the port with the charging symbol above it. It now works.

FYI - my monitor is actually a Sony TV and I'm using an HDMI cable with an adapter for the USB-C port.

FIXED!!! While everything is plugged in and on! Simply unplug just the power from your external and then plug it back in. Do not put in standby by or unplug anything else. It worked for me and hundreds of others after literarily trying all this other mumbo jumbo.

Yes, 12.3.1 fixes the two displays on an Intel MacMini issue that they created in earlier versions of Monterey.

Two displays now work for me the same as they did up to Big Sur. If only I could get the day of my life that I spent last week upgrading to 12.3 and then downgrading back to Big Sur.

Question for me is how does an organisation the size of Apple inflict an OS release on customers without testing that it doesn't actually break fundamental things on very common configurations of their recent hardware.

I moved from HDMI cable to DisplayPort and it worked. Purchased a USBC to DisplayPort cable for $13.00. No gongle.

I fixed it, my IT advised me to use the recommended docking station (Targus DOCK190 in my case).

I have 2 monitors connected via hdmi to it and just one thunderbolt connection to the mac.

I had all the same problems. Fixed with a switch from HDMI, to a USBC to DisplayPort cable. $14 on Amazon. No Dongle.

After installing 12.2.1 I now have both monitors operational... I did have to unplug and plug in my USBC dongle monitor but it is working now.

Downloading a new DisplayPilot driver for my BenQ monitor and power cycling fixed the issue with my 2020 intel iMac and 2nd monitor on Monterey 12.2.1