Apple Studio Display only works on certain USB-C Ports

[smirking]

About six months ago, I started having problems getting my Apple Studio Display to turn on when I plug it into my MBP. It's actually connecting, but the screen is dark.

It seems that MacOS thinks I'm in mirrored displays mode when I plug the cable in on specific USB-C ports and because my laptop is closed, the screen is dark. The ASD screen would be considered the second screen and it's off because it's mirroring a screen that's also off. If I flip open my laptop the ASD screen will also turn on, but as soon as I close the lid, the ASD screen goes off as well. My computer isn't actually asleep at this point. I've mashed my keyboard in frustration before I figured out what was going on and later found a document that I had open had lots of random characters.

To fix the issue, I just unplug the TB4 cable and put it into the other USB-C port. It'll now realize that I'm trying to use my external display in clamshell mode. The weirdest thing is that it's not always the same USB-C port that's affected!

The only variable I can think of that might be an issue is that I regularly plug a wired USB-C keyboard into my MBP when I'm not hooked into my ASD. It could well be that in the short period of time that I've moved from using an external keyboard to plugging into my external display, MacOS gets confused if I've chosen the same USB-C port that my keyboard was plugged into just a minute ago.

If I power cycle my ASD, it will also start working normally as well. This started with my M1 Pro MBP on Big Sur and the issue has followed me to my M4 Pro MBP on Sequoia.

Has this happened to anyone else or does anyone have any ideas on how to fix this? It's super annoying.

 

[Sheepish-Lord]

Maybe a silly question but are you using the supplied cable that came with the ASD and are you plugging it into the TB3 port that has the lightning bolt over it? When troubleshooting I always go back to basics and remove any variables (docks, 3rd party cable, peripherals, etc)

If you think it's the OS and the keyboard try plugging your keyboard into the other side and see if the symptoms are the same. Overall, what you're describe would definitely be abnormal and doesn't make sense from an OS standpoint.

 

[smirking]

Maybe a silly question but are you using the supplied cable that came with the ASD and are you plugging it into the TB3 port that has the lightning bolt over it? When troubleshooting I always go back to basics and remove any variables (docks, 3rd party cable, peripherals, etc)

Yup, using the original cable. If it were a cable issue I wouldn't get different results depending on the port.

Overall, what you're describe would definitely be abnormal and doesn't make sense from an OS standpoint.

Absolutely bonkers. I only post my craziest issues here!

FWIW, the last time I plugged in, I had all ports working fine. One thing that was different was that I had left my laptop asleep for a good long time before I went to the external display. Usually there's less than a minute between the time I disconnect my external keyboard and plug into my ASD.

I'm going to remember which port I plugged my keyboard in the next time I try to move from laptop to monitor.

I also just installed the most recent update to Sequoia so it could also be that whatever I was experiencing was fixed by the latest update.

 

[uller6]

Check for lint in the USB-C port.

 

[smirking]

Check for lint in the USB-C port.

OK, there's no way this is a troubleshooting step that would cross most people's minds. There has to be a good story here. We gotta know.

FWIW, I think the latest update to Sequoia fixed it. I haven't had this problem since I updated to Sequoia 15.3.

 

[smirking]

OK so it appears that the issue isn't fixed. It appears intermittent and seems to be very random.

The issue also seems to have changed a bit which might be an improvement. Before I noticed that one port or the other would not wake my ASD. When I get the problem now, if the screen doesn't wake, I just unplug and plug it back in. It doesn't matter if I move the TB4 cable to the other port or not. It just needs to be disconnected momentarily and the second time always works.