MacBook Pro M1 Pro issue with dual display after updating to macOS Sequoia 15.1

Finally the issue for me is solved. Instead of using a HDMI to USB-C adapter I purchased a DisplayPort 1.4 to USB-C adapter connected to the Dell G3223Q 32" and no more issues. I also deleted the display preferences files in MacOS:

/Library/Preferences/com.apple.windowserver.displays.plist

/Users/<YourUser>/Library/Preferences/byHost/com.apple.windowserver.displays.<ALPHANUMERIC_CODE>.plist

In the last case, it can be multiple files.

And then restart. I hope it can help

Found a temporary (not ideal) workaround on Reddit:

Basically go to your display settings and manually turn down the refresh rate for your external monitor. On Reddit people who had 144Hz and above weren't getting it to work, but turning it down to 120Hz brought it back to life. For my Dell monitor, I had to turn it down from 60Hz (my maximum) to 30Hz, which looks jittery and terrible, but at least it's kind of working. Hoping this will be fixed in the next patch because it's really bad.

"Finally the issue for me is solved. Instead of using a HDMI to USB-C adapter I purchased a DisplayPort 1.4 to USB-C adapter connected to the Dell G3223Q 32" and no more issues. I also deleted the display preferences files in MacOS:

/Library/Preferences/com.apple.windowserver.displays.plist

/Users/<YourUser>/Library/Preferences/byHost/com.apple.windowserver.displays.<ALPHANUMERIC_CODE>.plist

In the last case, it can be multiple files.

And then restart. I hope it can help

(2)"

This worked for me! Thank you.

Macbook Pro M3 with 15.1.1 installed, did what was suggested above, restarted and reset the settings as it was showing me an ungodly horrible view with my 49" Samsung connected via USB-C to Display Port which is the only way to get the 5120x1440 resolution. Once all reset, 240Htz and Clamshell mode operating as it should. Still filing complaint via the Product feedback page.Bug report submitted, thanks for the help Fam.

My 23" Apple "play" display is connected directly to my M1 laptop with a DVI-to-USB-C adapter.

The 'going dark every few minutes" problem is still not fixed in Sequoia 15.4 ...

I have found a work-around ...

I did several things that did not work, but who knows, may have contributed to the fix:

• pounding my fist on the desk and yelling the F-word every time the screen went blank. For two weeks.

• switched my Benfei DVI adapter to a Kanex DVI adapter, then back again. Yes, I know, both non-Apple.

• trashing display settings (you have to use Command-Shift-Period to show hidden files) ... and Restarting

/Users/<YourUser>/Library/Preferences/byHost/com.apple.windowserver.displays.<CODE>.plist

None of the above resulted in any change.

Other posters on this thread suggested changing refresh rate helped.

That does not seem to be an option on my display.

Here's my work-around:

• System Settings, Displays, Advanced, turn on Show Resolutions as List, click Done

The list appears at the top. Ten years of using this display and I'd never seen this list.

The default for my display is 1920x1200. I changed it to 1280x800.

While not ideal, I'm productive again, and I can rest my fist.

By the way, I think 1280x800 is the same as the laptop built-in display.

This glitch is simply not a hardware problem --

It's a Sequoia problem with video ("VRAM") management.

Apple needs to fix this!

Had the same issue after the update to Seqoia 15.1, when connected to the monitor using USB-C.

When I use HDMI (with adapter Thunderbolt - HDMI, my MacBook only has two Thunderbolt ports) the monitor is again working fine.

Should be fixed by Apple, I think.

2020 MacBook Pro M1, connected directly to AOC monitor via the USB-C/USB-C.

Has been working perfectly for the past year, but immediately after update to Sequoia 15.1, my external goes black for a few seconds intermittently. Extremely annoying.

Tried most of the common solutions offered online (check cables, try in safe mode, try new user account) but alas. Then connected via HDMI with a dock and no more issues. So seems like a software issue to me.

I hope Apple fixes this soon, because I liked that the single cable USB-C/USB-C setup also charged the MacBook.

RESOLVED (for me, for now)

I've been watching this thread because I have had the same problem everyone else has. Here is my setup:

MBP M1Max

3 identical LG 1920x1080 monitors (27MN60T)

Main display (center) uses HDMI to HDMI

Extended displays use HDMI to USB-C

Refresh Rate: 75hz (on all three)

Color Profile: LG FULL HD

No docking station.

Because MacOS can get confused on waking and swap my 2 extended displays (its own frustrating bug that has been present for at least the last 2 operating systems), I HAD been using VGA to USB-C by way of an adaptor for 1 of the 2 extended displays. That is the screen that was blacking every couple minutes once I updated to 15.1. As I was trouble shooting I noticed that screen was fixed at 60hz refresh with no option to adjust to the 75 the other 2 used. I bought an Anker HDMI to USB-C cable assuming that as long as I was replacing a cable I would try a decent quality one rather than the least expensive.

I have been running now since Saturday with no screen black out. I have no idea if this will help others or not, but thought I would share, just in case it might. (also posted in another similar thread)

Just installed 15.3 and the issue has been resolved for me. I can sadly no longer use my LG screen with 240 Hz (only 144 hz now), but this is more than fine, since I use 240Hz only when gaming on my PC. Finally!!

I was having this issue running 3 external 4K monitors through an "iVANKY FusionDock Max 1" dock and routed through an HDMI KVM. At first, I thought my issues were due to my Thunderbolt to HDMI cables or my KVM setup.

I tried multiple fixes, but ultimately, the problem was only solved after switching to the Apple 1M Thunderbolt 5 pro cables between my dock and my M3 MBP instead of the cables that came with the dock.

Apple definitely needs to develop a software fix, but for those dependent on external monitors, this might be an (expensive) workaround.

I tried other cables, even those marketed as Thunderbolt 4 and 100GB USB-C, and even reverted to MacOS 14.7 for a while; this was the only fix that worked for me while running MacOS 15.1.

Having serious flickering and black screen problems on Sequoia 15.1 and 15.2 as well.

My monitor was connected to the DP port of my Anker 778. I had to switch to a direct usbc-to-usbc connection between my MBP and the monitor (Asus PC279CRV).

I'm happy to report that since Sonoma 15.3 everything works correctly again. I'm back now to my usual DP connection through the Anker 778 docking station. 😊

Same problem for macOS 15.4 on Intel Mac with a discrete AMD GPU, my 4k display with a maximum 65W output charger, once my Mac battery is not full, I must use/plug an external charger (96W), then the display works. In previous systems like Catalina and Big Sur, there have been no such serious problems, the type C can offer 65W output which is quite enough to support the mac and display running.

Updated to Sequoia 15.3 => Issue solved. Connected to monitor just by using USB-C cable.

Similar problem with MacBook Pro 15-inch 2018. Rebooted after the upgrade to Sequoia 15.1 and the external LG 24-inch monitor purchased from Apple went black. Spinning beach ball when attempting to open Outlook (Mac version) and System Settings would also freeze.

I have 4 USB-C ports (two on each side of the MacBook). I was informed that the two USB-C ports closest to the rear of the keyboard were to be used to power external devices. That seems to have reversed. I resolved the issued by plugging the external monitor into one of the ports nearer the front of the keyboard, and it seems to be working without issues (at least for the past 20 minutes). I will update if the problem returns.

Ok, so I have done some massive re-plugging of cables and I may have found something, that can help some of you.

My Setup:

M1 Pro MBP 14" + Anker TB4 Dock + Dell 4k + LG 2k screen (240Hz)

I have removed all HDMI Cables from the setup and I connected the LG Screen via DP to DP Cable to Anker Dock. The Dell Screen is connected with DP to USB-C cable to the dock. Here is the interesting part:

When I connect both displays to the dock and then connect the MacBook, the Dell screen (connected with DP to USB-C to Anker Dock) keeps turning on and off every few seconds. The LG Screen is fine and it shows 144Hz Refresh rate.

When I unplug the dell screen from the Dock and THEN connect MBP to the dock, then the LG Screen shows 240Hz rate and it still works fine. Then I connect Dell screen to the dock and it almost never flickers. Maybe 1-2h per hour. AND the LG Screen works with 240Hz still.

So, connecting the MBP first, then plugging the dell display might alleviate some issues until the update is out.

Hope this helps!