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

Hi one more time,

Still discussing with Apple, they tell me I need to talk with LG, this is incredible, thousands of people with this kind of problems and in the support center they tell me that they dont have any notification, please guys open support tickets to apple so they can not deny this situation.

Ok this is what my diagnostic TV says about signals connected to it.

Windows PC to HDMI 2 rsult (in spanish) "Signal is OK"

Diganostic result from HDMI 3 where my apple macbook pro is connected "Signal is not as expected standard HDMI signal"

The message of the error

Honestly I dont think apple cares about this because it comes in Sonoma and continued in Sequoia.

Regards.

My Thunderbolt monitor (2012 model) did the same and now stopped working completely. The MBP does not even detect it. Yet, when I connect to older laptop with older OS, it works perfectly, so not a hardware issue. Agree that Apple has to fix this problem, but seems like they have no intention to do so.

This remains a most frustrating issue! (c'mon Apple, Fix this macOS bug!)

MY NEED: Mirror a MacBook Pro 16 (M3 running Sequoia 15.4.1) on a big screen TV at my local library via HDMI cable.

_____________

FIX SUMMARY:

Hit the *SCREEN MIRROR* icon on your menu bar after plugging in the HDMI cable connected to a working display device. See image at https://app.screencast.com/uzlkk6ySs2owb or below:

SCENE: TV works, HDMI cable works, a nearby WINDOWS Laptop works -- all those elements work in plug and play mode.

PREREQ: I did as Luis, above, suggested: SYSTEM SETTINGS>Privacy and Security>Accessories>Automatically allow when unlocked

OUTCOME: MacBook screen looks good on big screen TV. (Note: after connecting successfully, I could go went to SYSTEM SETTINGS>Display and found a new option (dropdown) that allowed me to optimize the TV image for either the MACBOOK or the TV. Play with it for best results.

Cheers! 😎

Have you tried AirPlay… see if the TV has that.

Having a similar issue on my MacBook M2 Max. I have 3 x external monitors, 1 x running on HDMI cable & 2 x running on USB-C to HDMI cables. The monitor running on the HDMI port has zero issues, the 2 running off the USB-C ports will turn on for a few seconds, I can see my desktops than both go black within a few seconds. I've tried everything and still have the same issues. Very 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.

Experiencing the same trouble here in MacBook Pro M1 Pro since 15.1. A 32'' 4K connected by HDMI with no issues and a 27'' connected by HDMI to USB-C adapter turning off and then turning on every few seconds. I am also noticing that the HDMI connector from the adapter is very hot, so I expect that no hardware troubles could happen.

Also having issues similar to the original poster since 15.0.1 to 15.1 upgrade on a 2020 M1 MacBook Air. Using a Dell 27" external display. My M4 Pro MacBook Pro does not appear to have the same issue (also on 15.1). Both difficulties getting it to send output via USBC to the monitor (monitor detects no signal) and the random external screen going black during use (intermittently).

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.

Nope, it's still not detecting.

I just updated to 15.1.1 and am using the Apple Thunderbolt, connecting with the Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter. It was working perfectly fine until they released Sequoia 15.

Very frustrating.

I just updated to 15.1.1 hoping that this would be better... but it's even worse! It won't display ANYTHING now (though when I plug the HDMI directly into the MacBook it's fine). And the Anker Dock Manager software now can't even recognize the dock even though it is currently charging the MacBook. Help!

Same issue here..... MacBook Pro M1, external screen Philips Widescreen....... Really I got a 2nd MacBook for work... but if I had that updated.. I really had a issue. Why does it take so long to fix.....

Same issue.

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

Worked great for the last year, but right after updating to Sequoia 15.1 my external screen periodically goes black for a few seconds. Extremely annoying.