MBP 14" USB-C display bug

[5425642]

Hi,
I have reported a bug to Apple now that I did found.
If you have a USB-C display that also include USB hub and charger it will not show any picture at the display it will just charge and you can use the USB hub inside the display.
It do work with the older M1 so the display are working also if I do connect HDMI or USB-C to DisplayPort cable then the display are working also.
Kind of frustrating.

If I did use the Belkin Thunderbolt Dock and connected the display to that dock with the USB-C I did also get strange issues like when I did reboot I was forced to open and close the lid to get picture again if I did not do that I did only have dark picture with the mouse showing only.

My Troubleshooting:
# Display
Dock:
Belkin Thunderbolt 3 Pro

Display:
LG UltraFine 32” 4K 32UN880

Display -> USB-C -> Belkin -> Thunderbolt 3 cable -> MBP 14”
If I connect the TB3 cable when the MBP 14 has the lid open it works until reboot then I need to open and close the lid to get it to work again.

Display -> USB-C -> MBP 14”
If I connect the TB3 cable when the MBP 14 has the lid open it works until reboot then after that it stops working. The same is if I disconnect the USB-C cable again then it also stop working.

Display -> Belkin with DP -> Thunderbolt 3 cable -> MBP 14”
Working

Display -> DisplayPort to USB-C adapter -> MBP 14”
Working

Display -> HDMI 2.0 -> MBP 14”
Working

Isolation:
* Tried with all the TB ports on the MBP14” same issue on all of them
* The display did work with all of the combos above with MacBook Pro 13” M1 that was running macOS 12.0.1

My guess is that it’s related to this;

macOS Monterey Users Report Connectivity Issues With USB Hubs

Some Mac users who upgraded to macOS Monterey this week are experiencing problems getting USB hubs and other USB-based devices to work properly with...

www.macrumors.com

 

[Saturnine]

Well it’s certainly not a universal issue. My USB-C monitor, with hub, works just fine.

 

[Teledatageek]

Sadly, I seem to have the same issue with my StarTech thunderbolt dock. The displays are there but shrunk and I can't seem to figure out a way to change. Must be a Monterey issue. I also tried plugging the Dell monitor in via direct USB-C with the same results.

So that same monitor is now plugged directly into my MBP 14 with an HDMI cable which yields a perfect single display. When I also (or without the HDMI cable) plug the USB C cable into the Mac directly from the Dell monitor - it breaks.

Sigh... good thing I'm headed on a week long trip tomorrow. We'll see if Apple fixes, otherwise might be back to my MBP 13 and return the MBP 14 until this gets resolved.

 

[matthewadams]

I'm chiming in here to report I'm getting intermittent blank screens or noise with a HP screen on a Caldigit TB3 dock. Still need to try a direct connection though to rule out its a dock issue.

 

[5425642]

Sadly, I seem to have the same issue with my StarTech thunderbolt dock. The displays are there but shrunk and I can't seem to figure out a way to change. Must be a Monterey issue. I also tried plugging the Dell monitor in via direct USB-C with the same results.

So that same monitor is now plugged directly into my MBP 14 with an HDMI cable which yields a perfect single display. When I also (or without the HDMI cable) plug the USB C cable into the Mac directly from the Dell monitor - it breaks.

Sigh... good thing I'm headed on a week long trip tomorrow. We'll see if Apple fixes, otherwise might be back to my MBP 13 and return the MBP 14 until this gets resolved.

Just so I understand you correctly.
When you connect your dell monitor with usb-c you don’t have any picture it don’t work.

When you connect it with hdmi then it work?

 

[5425642]

I'm chiming in here to report I'm getting intermittent blank screens or noise with a HP screen on a Caldigit TB3 dock. Still need to try a direct connection though to rule out its a dock issue.

Please do, try it out with usb-c and then report back.

 

[5425642]

Well it’s certainly not a universal issue. My USB-C monitor, with hub, works just fine.

What display do you have?

 

[Teledatageek]

Just so I understand you correctly.
When you connect your dell monitor with usb-c you don’t have any picture it don’t work.

When you connect it with hdmi then it work?

Clarifying - when connecting to USB-C directly or via the dock the screen on the external monitor is small. I tried when I had the HDMI connected directly and when I connected the USB-C directly to the Mac the screen reduced.

Weird stuff.... I wish I hadn't installed the Monterey update before connecting to the dock. Wondering if it's the update or Monterey that is doing this.

 

[5425642]

Clarifying - when connecting to USB-C directly or via the dock the screen on the external monitor is small. I tried when I had the HDMI connected directly and when I connected the USB-C directly to the Mac the screen reduced.

Weird stuff.... I wish I hadn't installed the Monterey update before connecting to the dock. Wondering if it's the update or Monterey that is doing this.

Same for me, I did update to the beta 12.1 and I don’t know if the issue are the update or if it was before.
One thing is for sure with my m1 it’s no issue at all.

 

[Teledatageek]

Same for me, I did update to the beta 12.1 and I don’t know if the issue are the update or if it was before.
One thing is for sure with my m1 it’s no issue at all.

Super frustrating... not sure Apple will act fast on this with an update. I hope so, otherwise I'll have to return the MBP 14. I'm presuming one can't downgrade to 12.0?

 

[Saturnine]

What display do you have?

LG 27UD88.

 

[5425642]

LG 27UD88.

Ok,
I have updated my Re-search and it do seem like a bug or what do you think?

# Display
Dock:
Belkin Thunderbolt 3 Pro

Display:
LG UltraFine 32” 4K 32UN880

Display -> USB-C -> Belkin -> Thunderbolt 3 cable -> MBP 14”
If I connect the TB3 cable when the MBP 14 has the lid open it works until reboot then I need to open and close the lid to get it to work again.

Display -> USB-C -> MBP 14”
If I connect the TB3 cable when the MBP 14 has the lid open it works until reboot then after that it stops working. The same is if I disconnect the USB-C cable again then it also stop working.

Display -> Belkin with DP -> Thunderbolt 3 cable -> MBP 14”
Working

Display -> DisplayPort to USB-C adapter -> MBP 14”
Working

Display -> HDMI 2.0 -> MBP 14”
Working

Isolation:
* Tried with all the TB ports on the MBP14” same issue on all of them
* The display did work with all of the combos above with MacBook Pro 13” M1 that was running macOS 12.0.1

 

[5425642]

Super frustrating... not sure Apple will act fast on this with an update. I hope so, otherwise I'll have to return the MBP 14. I'm presuming one can't downgrade to 12.0?

I updated my first post and as you can see all of my issues are related to the USB-C connect don't matter if it's connected to a dock first or directly in to the MBP 14" the issue are similar.
My guess is that it's a bug.

 

[deleon]

I am having a similar problem. My USB-C monitor will sometimes show the picture and sometimes not. When I wake it from sleep, there are times the monitor won't turn on.

Unplugging/plugging in the usb cable on the computer sometimes makes it start working again.

The only way to always make it work again is to power down the external monitor. Then turn it on. It will reconnect to the computer and work.

 

[5425642]

I am having a similar problem. My USB-C monitor will sometimes show the picture and sometimes not. When I wake it from sleep, there are times the monitor won't turn on.

Unplugging/plugging in the usb cable on the computer sometimes makes it start working again.

The only way to always make it work again is to power down the external monitor. Then turn it on. It will reconnect to the computer and work.

I have been reading many articles now and it do seem that it’s a bug in macOS 12

 

[matthewadams]

Please do, try it out with usb-c and then report back.

Alright, been running it for the past 30 minutes and so far no drop-outs. If this was HDMI via the Dock I'd have seen at least 1 or two by now. so knock on wood.

Annoying though, because I can say bye bye to the one-cable solution or might have to opt into buying a TB4 dock.

 

[Teledatageek]

Alright, been running it for the past 30 minutes and so far no drop-outs. If this was HDMI via the Dock I'd have seen at least 1 or two by now. so knock on wood.

Annoying though, because I can say bye bye to the one-cable solution or might have to opt into buying a TB4 dock.

I see the TB4 guys are saying they support the new Macs. So does that mean these other docks have a firmware issue or something? I still don’t get why my USB-C connection right into the Dell doesn’t work though

 

[matthewadams]

I see the TB4 guys are saying they support the new Macs. So does that mean these other docks have a firmware issue or something? I still don’t get why my USB-C connection right into the Dell doesn’t work though

You could try going to "About This mac" (apple logo) -> System Report -> Graphics/Displays and check if anything is different there in HDMI vs. USB-C connection?

 

[Teledatageek]

I see the TB4 guys are saying they support the new Macs. So does that mean these other docks have a firmware issue or something? I still don’t get why my USB-C connection right into the Dell doesn’t work though

Also just saw these docks aren’t available until February!

 

[Teledatageek]

You could try going to "About This mac" (apple logo) -> System Report -> Graphics/Displays and check if anything is different there in HDMI vs. USB-C connection?

Didn't seem like anything different when I checked About This Mac. However, when I plugged in this time, direct with USB-C to the monitor, it works fine. The part that doesn't work is the split screen/dual input part into the Dell monitor. With that activated, both sides of the screen shrink.

Then I got to thinking maybe it was the Dell firmware, there was an update which I applied, but nothing changed. I'm going to call StarTech support when I get back from my trip and see if they know of anything.

Something is goofy still but better than it was before.

 

[matthewadams]

The part that doesn't work is the split screen/dual input part into the Dell monitor. With that activated, both sides of the screen shrink.

Can you elaborate? What does split-screen/dual-input mean in this context?

 

[brookter1]

No problems whatsoever with a MPB 14” Pro connected to an LG27UP800 (with its own USB hub integrated) via USBC, either directly or through a Caldigit TS3 plus.

 

[tmoerel]

Strange. I am having no problems at all with a LG 27UK850-W either connected directly via USB-C or either connected via a OWC Thunderbolt 4 hub as well as a OWC Thunderbold 4 Dock.
In all three cases it works (even have some devices plugged in the USB-A on the back of the LG) using the original USB-C cable provided by LG.

 

[Teledatageek]

Can you elaborate? What does split-screen/dual-input mean in this context?

Sorry - my set up is confusing. I have a Dell U3818DW that has multiple inputs. When using two inputs, you can split the screen 50/50 which provides the same as two monitors in one. I know many just use one big screen but this works better for me.

In the StarTech dock - it uses USB-C and DisplayPort for the video out to the monitor.

 

[matthewadams]

Sorry - my set up is confusing. I have a Dell U3818DW that has multiple inputs. When using two inputs, you can split the screen 50/50 which provides the same as two monitors in one. I know many just use one big screen but this works better for me.

In the StarTech dock - it uses USB-C and DisplayPort for the video out to the monitor.

Ahh, thanks for clarifying.

For what its worth, I've so far read about one particular dock (Anker Apex) that supports multiple outputs that doesnt work with M1 Macbooks. instead of multiple outputs it just mirrors the same display across all ports apparently. Could be related but doesn't have to be...