M1 MBP Screen Flickering, External Monitor Crashing, & Unable to Connect to Apple Watch

UPDATE: Since updating to Big Sur v 11.2.1 my monitor connection / flickering / display issues have been resolved. I simply ran the software update that was recommended and the problems were fixed. Hope that helps someone else!

M1 MacMini, 16GB, 1TB and I also had a very similar issue with flickering when connected via HDMI to a Dell U2718Q (a 4K monitor). The monitor would flicker every minute and occasionally go completely black for 1-2 seconds before coming back.

A solution that appears to be working for now is a CalDigit USB-C Pro dock... I connected the dock to my MacMini with a Thunderbolt 3 cable. The dock is connected to my monitor using a Display-Port cable. So far... a few weeks and no issues.

I don't have a need for more than a few ports so the dock is otherwise an expensive paperweight for me. I would love to use a HDMI cable and ditch the dock... hoping Apple resolves in the future.

You are spot on. I had an old "High Speed" HDMI cable attached to my LG 27GL850 through a Dell TB16 Thunderbolt docking station on my new MacBook Pro M1. It was flickering and had artifacts. Sometimes it would even do the old school analog noise, almost as if it was an eighties television not connected the antenna. Saw your post, ran down to the electronics shop, got my self an "Ultra High Speed" HDMI cable (Up to 8K 60Hz) and waddayaknow.... Boom. Rock solid and stable. Although somewhat ambigous, it seems that what is referred to as "High Speed" support 720p and 1080p in 30Hz. Happy days!

SOLVED!

I had a similar/same issue: M1 Macbook Pro screen flickering when plugged in to HDMI external monitor through the Digital AV Apple Adapter.

I noticed that the screen flickered when I stood up and went to sit down. I figured it might be the proximity sensor. And it was! So when you rub over your webcam, you can trigger the flickering! You can even see it being triggered if you open up the display settings and see the brightness bar automatically adjust itself as you are rubbing your webcam.

If you open your Display settings and switch off "automatically adjust brightness", the flickering will stop.

Hello,

I had a similiar flickering external display issue:

MacBook Air M1

Dell U2027Q 4K

Connection via USB-C

Disabling True Tone and/or automatic brightness adjustment improved the situation.

The best results were achieved by enabling HDR in the Dell display settings as well as in the MacBook Air settings, though. In addition I started to shutdown the MacBook instead of hibernating. Currently I have no issues, even with True Tone and brightness adjustment enabled.

I am MacUser since 1994 and only on the Amiga I had more flickering :-).

Here is my solution:

Only display port works. You need a USB-C to Display Port adapter. It plugs into the Thunderbolt port. Everything else didn't work for me.

Also, an Elgato Thunderbolt dock works.

https://help.corsair.com/hc/en-us/sections/360010576211-Corsair-Thunderbolt-3-Dock

I installed last night the 11.2 BigSur update, and so far all my external display problems have vanished. I'm still testing for the flickering.

My flickering and wrong resolution problem was solved with the latest 11.3 update, you should give it a try. For me I'm relieved that it was a software issue.

I have the screen flashing issue as well and indeed hope that it is purely software based (and hope apple will look into it). The watch issue however does have an easy fix (or it was for me). You need to make sure when checking te box "use your apple watch to unlock..." that your watch is only connected to your phone and that both your phone and your watch are unlocked. After this I was able to enable this setting.

I might have had some success but its still early days, I still got the flicker with the DP cable but also started getting the resolution changing on the monitor when it went to sleep and so i'd have to power cycle it so sort that out.

I went back to using the HDMI cable. Over the weekend i connected a couple of hard drive (one usb 2 and the oher USB c) and a bluetooth sound bar. That's when the bluetooth connectivity issues started. Keyboard and mouse reconnecting every 20 seconds or there about. Disconnected the hard drives and things sorted themselves out. I spoke to a friend who's son had the same problem with a macbook, Apple told him to use the other usb c port. So i tried that and it sorted out the bluetooth issues, i also seem to no longer be suffering from the intermitant flickering on the monitor.

I'm using the usb port nearest the corner for one of the external HDDs, the HDMI cable to the monitor and the USB C port next to the HDMI port, I've a usb c splitter to two usb 2 ports, one for the other external HDD and the other just to power the blue tooth sound bar.

I'm not wanting to swap anything about as i might reintroduce the flicker. I spoke to Apple supoprt and i might have got it wrong but the flicker and bluetooth issues might be related.

Anyway just thought i'd share my experience.

I also witnessed this problem with the flickering of my MBP screen when connected to an external monitor. The monitor (LG HDR WQHD) was connected through a GC adapter on its HDMI port (50 MHz) and worked fine while the MBP screen flickered occasionally. The recommendation to switch off the Auto Adjust Brightness seems to eliminate the problem, at least in my case. I have also switched off True Tone and adjusted the monitor colour to match my preferences as I use it as the main screen considering the tiny space available on the 13" MBP.

I can see, reading the posts here, that this problem is present since the product started shipping. I got mine (MBP 16 GB RAM/1TB) after nearly two months of waiting and the problem is still there. That is a serious flaw and should be identified by now.

What worked for me was using a Displayport cable and switching the external monitor to Displayport 1.1 stream. I was using the Displayport 1.2 which caused a lot of flickering.

i have the same monitor , adjust the sharpness on the monitor from 5 to 7 , problem has gone for me so far.

Try turning the true tone off. That stopped my external display from flickering, though it is annoying as it also disables true tone on the Macbook.

I have the same issue with samsung s3221qs monitor. I figured it out by turning of true tone feature while using both screens. Hope this helps