External Monitor Issue After macOS Sequoia 15.1.1 Update

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.

I have the same issue and I use an LG Ultra 4K connecting directly with a USB C cable (not using a dock) to a Macbook Pro.

I have the same issue and I use an LG Ultra 4K connecting directly with a USB C cable (not using a dock).

Same issue for me the moment my MacBook Pro update to 15.1.1. LG monitor flickers and comes on for a second then black screen. Worked flawlessly up until now and I've tested several other monitors with the same results. since I use an external monitor for work all the time. Seems like this would be a massive widespread problem. Hope this gets noticed and fixed asap!!

[Edited by Moderator]

Same problem as all the others. WIsh now I hadn't updated. Other things have changed and quit working as well but this is the most important one for me. I use two monitors in addition to my laptop. This is for business - not for games. When will Apple respond? Better be soon or I will stop heralding Mac's value to everyone I know! Shame on you Apple for not doing your job properly. Not the kind of quality I have experienced over the last 25 years of Apple ownership!

Thank, and Happy Thanksgiving to you, too!

I can confirm that this dock does rely on DisplayLink, and that could be part of the problem.

As far as I can tell, you are downloading from the proper location. They do say they support Sequoia.

I don't know if it is something with the software or the dock itself, or a combination of the two.

Have USB-C dock connected. Worked fine yesterday, now it's working as by described others. I switch back and forth between my work Windows laptop and my personal Mac Air M2. Works fine on Windows laptop but not on Mac Air 2. Is there a way to go back to previous version of Sequoia or is there a fix coming anytime soon?

I have same issue after update my os. 15.1.1 since last week. But today my Mac book pro 2019 T2 chips built in display starting to glitch and flickering look like my display is broken. I tried again and again but still happening, I hope it will be okay soon, please check and photo also. I don’t have any money for changing new display and quite expensive though. I wish and I hope Apple can be repair this issue soon.

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,Before the update to macOS Sequoia 15.1.1, it worked perfectly. After updating, the same problem occurred.

I now remembered what I did to fix the issue last time this happened after a MacOS update:

Power your monitor off and turn it on again.

Sadly 15.2 didn't work for me; still an issue. Tried with usb-c adapter in one port and charger in the other, same result. Tried rebooting with external monitor connected, made no difference.

TxPomeroy wrote:

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?

Tell us the exact model of your dock, and should be able to determine if it uses DisplayLink

Reply to: External Monitor Issue After macOS Sequoi… - Apple Community

I now remembered what I did to fix the issue last time this happened after a MacOS update:

Power your monitor off and turn it on again.

Didn't work for me...

Hi all,

Same issue here --> Macbook Pro 2018 Intel I7 with T2 Chip

• Happens with:
  • Original Apple USB-C to AV digital (see screenshot)
  • Other USB-C HDMI adaptors
• Tried
  • Change cable
  • Change adapter
  • Change refresh rate
  • Reset NVRAM
  • Reset SMC
  • Pray....

Nothing works, have we an estimation of when this issue will be solved?

Regards.

Exact same issue for me as OP. After updating to Sequoia 15.2 (I don't recall what the previous version was), the flickering issue occurred immediately after the update. Nothing else has changed about my set up after the update, so I feel very confident that the 15.2 update is the root of the issue.

Here's my set up prior to Sequoia 15.2 Update:

• Macbook M1 Max, 16-inch, 2021
• MacOS Sequoia 15 (not sure which previous version)
• External displays:
  • Working normally: "Display 1", LG 27GN650-B (connected via HDMI port)
  • Malfunctioning, flickering: "Display 2", LG 34UM69G-B (connected via usb-c port, USB-C to USB-C display cable)

Steps that failed to resolve issue:

• Follow steps 1-4 outlined here. Did not resolve issue.
  • Unplug cable and monitor power cord
  • Mac is already at latest update
  • Restart Mac
  • Change color profile of external monitor to Color LCD
  • Change refresh rate to 60 hz
  • Disabled true tone/night mode where applicable
• Changed USB-C cables, and tried plugging USB-c cable into different USB-c ports. Neither resolved issue
• Swapped display cable from USB-c/USB-c to USB-c/DisplayPort. Did not resolve issue.

Steps that resolved the issue so far as of Dec 19, 2024 at 11:06:

• Swap display cables between Display 1 (working) and Display 2 (malfunctioning):
  • Display 2 is now connected via HDMI cable to mac HDMI port
    • Color profile: Color LCD, 60 Hz refresh rate, no true tone/night
  • Connect Display 1 via DisplayPort to USB-C mac port

Since swapping display cables between external monitors, the flickering has stopped. I will update accordingly if anything changes.

Exact same issue for me as OP. After updating to Sequoia 15.2 (I don't recall what the previous version was), the flickering issue occurred immediately after the update. Nothing else has changed about my set up after the update, so I feel very confident that the 15.2 update is the root of the issue.

Here's my set up prior to Sequoia 15.2 Update:

• Macbook M1 Max, 16-inch, 2021
• MacOS Sequoia 15 (not sure which previous version)
• External displays:
  • Working normally: "Display 1", LG 27GN650-B (connected via HDMI port)
  • Malfunctioning, flickering: "Display 2", LG 34UM69G-B (connected via usb-c port, USB-C to USB-C display cable)

Steps that failed to resolve issue:

• Follow steps 1-4 outlined here. Did not resolve issue.
  • Unplug cable and monitor power cord
  • Mac is already at latest update
  • Restart Mac
  • Change color profile of external monitor to Color LCD
  • Change refresh rate to 60 hz
  • Disabled true tone/night mode where applicable
• Changed USB-C cables, and tried plugging USB-c cable into different USB-c ports. Neither resolved issue
• Swapped display cable from USB-c/USB-c to USB-c/DisplayPort. Did not resolve issue.

Steps that resolved the issue so far as of Dec 19, 2024 at 11:06:

• Swap display cables between Display 1 (working) and Display 2 (malfunctioning):
  • Display 2 is now connected via HDMI cable to mac HDMI port
    • Color profile: Color LCD, 60 Hz refresh rate, no true tone/night
  • Connect Display 1 via DisplayPort to USB-C mac port

Since swapping display cables between external monitors, the flickering has stopped. I will update accordingly if anything changes.

Update Dec 19, 2024 2pm: Unfortunately, the flickering still occurs but it's less often and less intrusive. The flickering happens maybe once an hour. And, instead of my mac thinking the display has been disconnected and rearraning all my open windows, it's just a brief off/on flicker and no windows move.