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Level 1

11 points

External display no longer recognized on MacOS 12.3

2018 Mac Book Pro 15" and I have 2 external monitors (same viewsonic model), have been using fine for just under 2 years. After updating to 12.3, one is recognized and one is not and I have no clue why. I have swapped cables, connected other devices, including a iPad Pro (all fine) I have tried all 4 ports on the machine no difference. The Mac book flashes when the unrecognized monitor is plugged in, but never displays an image. the monitor seems to think it's connected (I don't get the no signal warning) nothing.... 8* the monitor is powered and the screen it bright (bleed from the backlight). The other monitor (same exact model) connects and works fine.

Do Macs just no longer like right side monitors?

What the heck did 12.3 do to my machine?

Posted on Mar 15, 2022 10:01 AM

Best reply

cowomo404 Author

Level 1

11 points

Posted on Mar 24, 2022 6:34 AM

Tried many of the suggestions below but none worked - I did solve my problem though. This is what I found - which may or may not be the same issue others are having.

My monitors are a 4k HDR panel - but I have previously turned off HDR on one of the panels (reasons not important).

My panel also doesn't allow access to the OSR without a video signal ... which made it a bit tricky to change the settings when it's not recognized; but using another machine I turned on HDR on the panel and the Mac instantly recognized. I didn't test this by turning it off again and instead just thanked my lucky stars - but it may be that the new OS requires HDR panels to send HDR signal ... or something like that. Sorry for other folks having trouble - my fix might be an area to explore.

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External display no longer recognized on MacOS 12.3

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