External Monitor Issue After macOS Sequoia 15.1.1 Update

Thanks for replying, in fact it happens to me in very new LG TV and in an old TV it does not happens. Super rare....

I have the same issue. Using an LG 24BP750C-B monitor with USB-C.

Monitor screen goes blank for a few seconds intermittently.

Upgraded to Sequoia 15.2 yesterday, no issues before this.

I think the trick was unplugging the power while using usb-c

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.

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?

Hours later, using the simple adapter from my junk box: one single event only.

Interesting that the box became a bit warm in the beginning, then it cooled down and stayed cool. Perhaps I should try the original adapter again ...

hi TxPomery that link to Lionwei is interesting but you say it has one HDMI port - I see two, do you use displaylink to overcome lack of MST , I am looking into an adapter for my M1 macbook air and want to use 2 or 3 external monitors displaying separate video , your link looks good but all these stories of flickering with mac OS updates sound a bit familiar - windows doesn't deliberately lock out functionality the way mac OS seems to

Yeah, it has two HDMI. Sorry if I gave you the wrong impression since I only need or use one. But, the Amazon listing shows you can have two external monitors but they'll show the same thing. Not a problem for me since that's all I need. This seems to have been a limitation of Macs for a long time. Even my 3 year old KVM/dock had the same limitation. I haven't used Macs long enough to know how you can get around this limitation. Good luck.

Since two days my primitive graphics adapter works well. Your link, TxPomeroy, wasn‘t helpful for me as Amazon unfortunately doesn‘t deliver it to Germany.

I‘ll await 15.1.2 now, in the hope, Apple will repair this bug soon…

Thanks for this! Quick question: are you only running one external monitor, and not multiple? I was able to run 2 before, and with the update, now only one works, and only one is detected by my mac. No issues with my DELL windows laptop.

Having the same issue here, there is a dead zone on my external monitor, upper left corner, where clicks just don't register. Can't tell you how frustrating and time consuming it is to have to move a toolbar or window just to click.

Running a Macbook Pro 2021 with an apple USB-C to HDMI adaptor for an ASUS external monitor.

Checking daily to see if there's a software update.

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!

tkatebini wrote:

Thanks for this! Quick question: are you only running one external monitor, and not multiple? I was able to run 2 before, and with the update, now only one works, and only one is detected by my mac. No issues with my DELL windows laptop.

Which mac? And how are the displays connected to your mac?

Did you update DisplayLink software, if you use that?

Same issue here - I can't connect my HDMI cable to a ASUS screen. The connection keeps turning on and off - it is just a endless loop, like 3 seconds between. I tried updating DisplayLink to the newest, didn't work... The monitor works on my Windows laptop...

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.