Monterey 12.0.1. Second Monitor Issue

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.

I made the upgrade just before Xmas break without checking properly how it was working,

Today, 1st boot, the mac gets stuck for minutes on every single click and suddenly my 2 monitors (connected via thunderbolt) start flashing and getting on and off.

It looks it works fine with just on monitor connected

MBP 16", Monterey 12.1

HP E27D docking monitor

Dell P2419H 2nd monitor

I have the same issue with 12.01 on my new MacBook Pro. And just to make it stranger: The (almost-new) monitor has two HDMI ports, and it detects the computer, but the computer doesn't detect the monitor.

Apple - this is ridiculous. My first comment on this forum, this issue was NOVEMBER 4. Tomorrow will be two months that I have been unable to use my external monitor. Surely you have people working on a bug fix? This is unacceptable and I am really disappointed. This is only the second time in nearly 30 years of working on Mac-based computers that I have been so let down, but this is a BIG PROBLEM.

All - Frustrated by the same issue we've all been facing with the 12.1 OS upgrade eliminating my ability for my MacBook Pro to connect to my 32" Samsung external monitor.... I tried every combination of everything. Different mac, HDMI cable, monitor, adaptors, etc... as we all have. Finally... in frustration I took a chance and overnighted in a DisplayPort to USBC cable from Amazon. Not all of you may have a DisplayPort on your monitor... BUT... I plugged it in and it worked just fine! SO happy.

SO... maybe the issue Apple has with 12.1 has to do with HDMI port connection via ANY means! Worth a try for you! Cables are cheap, and I ordered the "USB C to DisplayPort Cable for Home Office (4K@60Hz, 2K@165Hz), uni Sturdy Aluminum DisplayPort to USB C Cable [Thunderbolt 3 Compatible] for MacBook Pro, MacBook Air/iPad Pro 2020/2018, XPS 15/13" for $13.59! No dongle needed.

I’ve spent time with the Apple help desk. We tried a number of things. But the best was to set up a new user with administration rights. Shutdown, login as the new user, then connect the external monitors, and swap back to my user ID. All a bit shonky, but for now it seems to be working.

I also installed this app which seems to be helping:https://github.com/waydabber/BetterDummy

I had another phone call from Apple senior support person. Now Apple denies the existence of the problem and blames the display manufacturer. Isn't it weird that this happens to all of us at the same time even with different monitor manufacturers?

Apple isn't the same company they were 5-10 years ago. Faulty OS updates, hardware issues, lack of cohesion and communication between customer service departments, Beta testing seems to be a thing of the past. They need to get it together, this is unacceptable.

I was having the same problem as everyone else is lamenting here. I finally noticed however that my Macbook was actually on battery power, though the power cable was attached, and in the settings for displays, for when on battery power, there is no option you can set to not sleep when the lid is closed. I had thought my laptop was on the wall power, so I thought the no-sleep option that is only active when on wall power, was active. It was not, and the laptop has a sensational battery life so I just did not notice until the battery was at 1%, when I thought, dag nab it, and looked under the desk to find the white power brick knocked akimbo from the socket. As soon as this was corrected, and the laptop was back on wall paper and the battery was charging, all the expected behaviors returned. The laptop secondary screen remained on when the lid was closed, and the device did not sleep, and therefore did not blank the screen. So, in my case, the entire brain-straining Apple-teeth-gnashing ordeal came down to not being plugged into power and thinking I was, the unobtrusiveness of being on battery power (I had settings to not dim anything or otherwise change performance on battery) and the long battery life. Problem thankfully solved, as least for me, and I hope for at least a few others.

Getting a bit off topic, maybe? The Apple platform is known not only for its quality of technology over Wintel but its civility of discourse, cultural integrity, and overall aura of uptone outlooks and classy behavior, vs. the sordid rabble of brylcreem & muscle-tees, hollering and fisticuffs making a racket over at PC High ... a contrast I hope you will consider helping to maintain.

Im sorry but that's just naive thinking and I strongly disagree. Don't want to open this thread up to Apple bashing, but it does need to be said. There are stark differences in product quality since the Jobs days. Update after update, Apple has proven unsuccessful in releasing a decent operating system that doesn't involve breaking legacy software/hardware. From AV plugins, to monitors not working, to spotlight breaking time and time again, to peripheral hubs getting out dated, to performance and lag issues. I can literally write a book about how many issues they have been having recently - which also worth noting were not a thing during the Jobs days. Overpriced machines? Fine, but at least deliver a product that is deserving of the eye gouging money they are asking for their products. I thought the high prices for Apple products were supposed to be synonymous with seamless integration between hardware/software, unrivaled support, etc. All of that is going down the drain, and I don't blame the several posts above me for being upset that this issue did not get caught during Beta testing.

This is getting even more ridiculous. I bought a HDMI-DisplayPort cable thinking that I could use that available DisplayPort to extend my screen to my Dell monitor while USB-C to USB-C to the monitor is working fine with peripherals (SSD, HDD). MacOS does not recognise the display! What the h*** is going on? Only thing working is HDMI-HDMI connection. APPLE FIX THIS PROBLEM ASAP!

I have a Macbook Air 2017. I updated to Monterrey 12.1 : the camera and the displayport output stopped working. Now I'm without a camera and I can't turn on my second monitor either!! I've tried ALL the tips on the internet (SMC, NVRAM, etc) and none worked. I tried formatting and reinstalling, but that didn't work either! I need help please!

I had this at first. I use a USBC/Thunderbolt Hub from OWC (Other World Computing). I noted that under System Preferences>Displays the external display no longer showed up.

I powered down my iMac and 21 "Cinema Display and unplugged them. I disconnected all cables from my USB-C/Thunderbolt Hub and disconnected its power source, as well. I restarted the iMac. I powered up the Hub and connected the cables. I powered up the the 21 " Cinema Display. Everything went back to normal . The display even showed up on System Preferences>Display, as before,.

I had exactly the same issues as everyone else on this thread, downloaded Monterey onto a 2015 macbook, and my 2x Dell 24inch external displays did not work. I tried almost every step that is listed on this thread with and without Apple engineers' help and nothing worked. I was just about to go back to a prior OS when an engineer asked me the simplest question, whether I'd reinstalled my drivers for the displays since the software update. I hadn't. We did this and it worked straight away. When i reboot the computer the screens do not work, but if I go to the display driver manager and double click it, then they come back to life. A bit of a faf, but much better than not having my screens. Maybe I'm the only person this helps, but if it helps one other person it has been worth writing it!! Thanks to everyone for putting their ideas down as well, it has been a very helpful thread in what has been an enormously frustrating 24 hours!!