Monterey Beta 8 - problems with external display

After updating to Beta 8, I can't seem to get my external display to work. The backlight on the monitor turns on and it seems to interpret some data from the MacBook briefly displaying a flash of colors and then going black with the backlight still on. The Display is still fully function on a different Mac.

Macbook Pro 2016, display connected to external thunderbolt 3 hub.

Answered by IgnacioAF in 689793022

As a workaround, I installed Beta 6 (complete pkg) over beta 8 to restore my display use. I guess the solution will be in the next beta (9).

This is so annoying and I know Apple doesn't really care since this is Beta code but I have been forced back to using a Windows laptop (Yuck) because it supports an external display.

Where can you download beta 6? Same display issue.

Beta 9, released today (Wednesday, October 6th), apparently resolved all this issue. I just installed it over Beta 6 and everything went ok.

Same problem here BETA 12 - Dell monitor connected with DP

Beta 9 installed over Beta 8 still exhibits this problem for me.

Hi. Macbook pro 15" late-2016 owner, experiencing same bug with both my Dell, USB-C 4k P2721Q and my Thunderbolt display (with USB-C adapter), on Beta 8.

Just updated to Beta 9 (released today) and it's now fixed!

I had this problem with beta 8. None of my external monitors would work, and the "workaround" also didn't work. I just installed beta 9, and I'm back in business.

I still have the issue with Beta 10 now.

Same problem for me. I have MacBook Pro M1 and LG 4K connected with usb-c thunderbolt cable. No video on external display.

MacOS Monterey 12.0.1

Same for me. Downloaded Monterey 12.0.1 on an older (Intel based) MacBook Pro with a Thunderbolt connection to a Lenovo P27h-20 monitor. Used to work perfectly on the previous OS; however, this time it is the laptop screen only...

Has anyone been able to confirm if the problem still exists in the full release?

Yip same problem here. Everything worked fine until I updated to Monterey this morning. Simply cannot get the monitors to work. Restarted. Unplugged etc etc.

Bizarrely it works when the MacBook is open. AS soon as you close the lid to work simply off the external monitors it stops working.

Same problem on Monterey release version. External monitor not working via HDMI-USBc adapter on M1 Macbook Pro. When I plug it in, CPU consumption grows a lot and monitor does not show anythong

I am experiencing the same issue. Apple is so good about fixing these types of things. I hope it gets cleared up soon. I need to switch between mirror and external display to get mine working after a sleep. UGGGGHHHH!!!! APPLE HELP!!!!

My external display stopped working immediately after upgrading to Monterey on day 1 (v12.0.1). Specifically, didn't display anything but was still recognized in System Preferences → Displays.

The fix in my case was to change the display's "Refresh Rate" from "Variable" to "60 Hz" (though I'm sure any of the fixed frame rates in the drop down would have worked).

Since Big Sur didn't offer the "Variable" option, I'm 99% certain the problematic setting was written by the Monterey upgrade routine, since it (correctly) detected that my monitor (an Acer B77 marketed as supporting ActiveSync) theoretically supported Variable refresh rate. But given the gap between theoretical & actual support for Variable refresh, it would have been nice if Monterey only overwrote that setting after confirming with me that the display still worked, as I never would have thought to check that setting if it weren't by luck that I happened to be looking for the new Variable Refresh Rate feature the first time I connected the external display.

I'm not sure where the problem is. I connect to the display indirectly via a Belkin Thunderbolt 3 dock and don't have the necessary adapters/cables to re-try the Variable rate option via a direct connection, so it could be the Acer display, the Belkin dock, Monterey itself, or some combination thereof.

Monterey Beta 8 - problems with external display
 
 
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