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Swkk Author

Level 1

32 points

External Monitor Issue After macOS Sequoia 15.1.1 Update

Hi everyone,

After updating my MacBook Air M2 to macOS Sequoia 15.1.1, I’ve encountered an issue with my external monitor. I connect my ViewSonic monitor via an HDMI-to-Type-C cable. The monitor works for about 5 seconds after being connected, then the screen goes black.

Interestingly, the monitor is still detected in the display settings, and I can even move the cursor into the display area—but nothing is visible on the screen.

Here’s what I’ve tried so far without success:

Adjusting the resolution and refresh rate.
Booting in Safe Mode.
Resetting display profiles.
Rebooting the system.

To rule out hardware issues, I tested the same setup on my MacBook Air M1. Before the update to macOS Sequoia 15.1.1, it worked perfectly. After updating, the same problem occurred.

However, I tried connecting to a Samsung external monitor, and that worked fine.

Has anyone else faced similar issues or found a solution? I’d appreciate any guidance or suggestions.

Thanks!

MacBook Air, macOS 15.1

Posted on Nov 26, 2024 8:50 AM

Top-ranking reply

MessyDuck

Level 1

14 points

Posted on Nov 27, 2024 1:43 AM

I have a similar issue. The external monitor that used to work fine prior to the update to macOS Sequoia 15.1.1 (LG 29UM69G), now flickers, i.e. goes off for about 2 seconds, then it goes back on. Happens on both my Macbook Pro M1 2021 and Mac Mini M1 2020. If I disable 'Prevent automatic sleeping when the display is off' in System settings, then my Macbook Pro goes to sleep when the flicker happens, ending any calls in the process.

This is completely random, it can work well for hours, or flicker every minute or so. I've been unable to link it to anything I do or have on my system.

Tried to change cables (USB-C, DisplayPort, HDMI), ports, screen refresh, and color profile to no avail.

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64 replies

abro

Level 1

13 points

Dec 13, 2024 12:49 PM in response to Swkk

The 15.2 update did not fix this issue for me. I only accepted the 15.1.1 update because I had a different issue related to iCloud synchronization of contact labels and Apple support insisted that I update to Sequoia. Now I have a new issue with my monitor while my original contact synch issue remains unresolved as well. Super cool!

617dev

Level 1

8 points

Dec 17, 2024 10:21 AM in response to Swkk

This is still an issue on 15.2. I've updated my M3 Macbook Air and a portable monitor that worked fined before updating via the same USB-C cable, now it only gets power (I see the monitor splash screen) but does not connect to my MBA no matter what port I try, I've tried rebooting, resetting PRAM, nothing seems to work. One time it showed the display for 3 seconds after rebooting while leaving the monitor connected and then it went black again. Also it connects fine to a dock I have that's connected to 2 monitors (via DisplayLink) and it connects to a different monitor via DVI to USB-C cable without issue, (that monitor is powered though). Maybe the issue has to do with transmitting the display signal and power via one cable, but prior to the update it worked fine.

I have confirmed this is working with my M1 Macbook Pro with the same version of Sequoia 15.2, so it almost seems like it's a specific issue with a combination of MBA M3 hardware (potentially other models too) and 15.2. I hope they fix it soon, because it's very frustrating.

Dec 18, 2024 4:59 AM in response to Swkk

This is incredible!!

I updated to 15.2 and the issue dissapeared for almost 4 days, and now it happens again.... how is this possible?, I contacted apple and they told me they dont have notifications about similar issue regarding Sequoia....

I will uninstall Sequoia and will try Sonoma.

Dec 18, 2024 5:52 AM in response to Janusromanus

Janusromanus wrote:

This is incredible!!

I updated to 15.2 and the issue dissapeared for almost 4 days, and now it happens again.... how is this possible?, I contacted apple and they told me they dont have notifications about similar issue regarding Sequoia....

I suspect this is more of a corner case for them, given the amount of activity I see on this and similar threads. So they don't really care. I haven't been actively gathering data, but does this look like it's only happening with older external hardware? My monitor certainly is old and I've no intention to changing it, for sure not because of poor drivers from Apple...

I will uninstall Sequoia and will try Sonoma.

I've been back on Sonoma for 7 days now and even installed a security update. I've been fine so far, issue seems to be gone.

Dec 21, 2024 2:50 AM in response to Swkk

After reading this thread I tried one more thing - replacing my $70 Mac USB-C to HDMI (Multiport) adapter with a much less expensive Anker USB-C to HDMI adapter and it fixed this problem. Something in Sequoia broke the mac version of this adapter, which is ironic considering it's so expensive. I also tested with a Nintendo Switch USB-C to HDMI adapter with the same results. The Anker and Nintendo adapters work fine, the disconnecting/blinking went away. Only occurs with the Mac brand adapter (MacBook Pro > Mac USB-C Multiport > HDMI cable > LG Ultrawide monitor).

Nov 28, 2024 7:15 AM in response to TxPomeroy

Maybe you have one of those docks that require "DisplayLink" software? If that is the case, make sure to update DisplayLink to the latest version.

Nov 28, 2024 10:25 AM in response to Luis Sequeira1

How do that on Mac Air M2? I've only had the mac since march. Still learning and system search didn't bring anything up?

Dec 1, 2024 3:44 AM in response to matsch57

I experienced the same initially when switching to HDMI using a cheap multi-functional adapter. For an entire day, no flicker! Then the next day, it started all over...

matsch57

Level 1

8 points

Dec 1, 2024 4:15 AM in response to MessyDuck

Really mysterious, I'll report in the next few days.

I just checked the refresh rates: the current adapter allows 30 Hz only

matsch57

Level 1

8 points

Dec 1, 2024 6:15 AM in response to MessyDuck

You were right, MessyDuck, but it took only a few hours until a new interrupt occurred. My very last adapter (dock for MBA) won't work better, I think...