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

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Similar situation. I have a Dell U4924DW. Since Sequoia 15.1.1 the monitor is not detected at all.

Incredibly frustrating.

This problem persists from day 1 of v15.1 when it was in early beta. I thought may be beta software issue & reverted back to public releases. But it seems like Apple has never fixed this issue for 15.1

I have a single Monitor hooked via DisplayPort to a USB-C Hub, which is connected via Thunderbold to my MacbookPro.

I face the same issue, that the monitor is going blank for a view seconds. Do you think it could help to switch to the HDMI Port? Or would I need to connect the mpnitor directly to the Macbook, which I wouldn't prefer.

Thanks for listening

Exact same issues here too!

I've been using the Apple Thunderbolt Display since 2016, and it's been fantastic.

However, it's recently started acting up. It began intermittently working and then stopping after the release of iOS 16 (Sequoia). I'm using an M1 Max chip, and the display worked perfectly for the past year or so.

Strangely, when I connect it to my older Mac Pro, it works fine.

I don't understand why it's stopped working with my M1 Max MacBook Pro.

I've heard that replacing the Thunderbolt cable (not the power cord) might fix the issue.

Do you have any suggestions on how to resolve this?

I've contacted Apple support in Korea, but they seem clueless about the problem.

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

That's why it seems to be issue with TB4 Docks. I have 2 screens connected to my dock. 1 Dell 27" 4k Screen with USB-C to Display port (this one works fine) and HDMI to HDMI on the 2nd screen, which is LG 27" 2k screen (this one flickers). Sadly, the Anker TB4 Dock only offers HDMI Out for the 2nd screen, hence I can't get around this issue.

I really hope Apple fixes this, the issue is really annoying.

Same problem here on an M1 MacBook Air. It's not all monitors though. It's just my 4K monitor that keeps disconnecting and reconnecting. My two 2.5K monitors seem to be fine.

Really frustrating as my 4K drawing tablet is now useless until this is fixed.

• correction: iOS 15

I have the same problem with an HDMI to USB-C adapter. It worked fine before 15.1 but now I can't use my external display. Does anyone find a solution ?

ZiaDaisy wrote:

• correction: iOS 15

Correction: macOS 15. iOS is the operating system used by the iPhone.

Have the same issue in Macbook M1 pro in 15.1 with LG ultrafine 21,5” 4k. Randomly the monitor connects and disconnects many times during the day.

It didn't work for me either. Strange that I left the screen still with Lungo and nothing happened. When I started working more, the blinking started... Soooooo annoying...