15" tMBP: External USB-C display not working properly after sleep with High Sierra

ManuCH

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Since upgrading to macOS High Sierra 10.13, I've been having an issue with my late 2016 15" MacBook Pro (Radeon Pro 455 graphic card).

I'm using it connected to an Asus MX27UC 4K USB-C display. After waking up the MBP from sleep, the external screen picture will not stay on. It will lose sync every 10 seconds or so, only to work again a couple of seconds later. It will basically flash on-off in a 10-2 second rhythm.

Subsequent sleeps and resumes, as well as unplugging and re-plugging the display to USB-C will not help. A reboot also won't help. The only fix is to shut down the MBP and start it up again. Then it will work - until the next sleep.

It seems like they screwed up the Radeon display drivers with High Sierra.

Is anyone experiencing similar issues with external displays?
 

ManuCH

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The problem is still there on High Sierra 10.13.1 Beta 1.

Update: this can also be reproduced by unplugging and re-plugging the display to USB-C while the Mac is running. It seems that it will only sync properly on the first time after booting. On subsequent syncs it will fail. Disabling "automatic graphics switching" to leave the Radeon 455 always on doesn't help either.

Has nobody else experienced this?
 

ManuCH

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Sorry for the thread bump - nobody? Can someone maybe confirm that such a setup (4K display connected via USB-C to a late 2016 15" tMBP) works for them?
 

bartvk

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Dec 29, 2016
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Don't have this issue but in my case there's an USB-C hub in between. I've got a Samsung LU28E590D, which is just plain DisplayPort or HDMI. I have noticed though that clamshell mode is a bit fiddly.

I always follow this procedure:
- open MBP and login with TouchID
- connect hub with monitor
- leave MBP open
- ... (work)
- disconnect hub with monitor
- close MBP

With Sierra, I've had a bit of trouble (including kernel panics) doing otherwise. High Sierra may have fixed this, haven't tested it yet.

By the way, you could try and remove monitor settings according to the following thread on Stack Overflow: https://superuser.com/questions/165108/misconfigured-external-monitor-on-mac-os-x-snow-leopard-10-6-3#172487
 

ManuCH

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Thank you for your response! Actually I noticed that if I use a USB-C to HDMI adapter the issue doesn't appear. It only happens if I use the display in its native "DisplayPort over USB-C" mode.

It's annoying having to use an HDMI adapter, though, as I lose the charging capabilities and I have yet to find a USB-C to HDMI adapter which supports 4K@60Hz out of the box (I always have to resort to workarounds like the SwitchResX app).

Thanks for the monitor settings instructions, hadn't found those yet and will give it a try!

Edit: unfortunately clearing the WindowServer preferences didn't help.
 
Last edited:

ManuCH

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Update: same symptom when using a USB-C to DisplayPort cable, or the DisplayPort output of an Elgato Thunderbolt 3 dock.

Also, booting from an external Sierra boot drive works perfectly. I've tried replacing the AMDRadeon kext files in High Sierra with those from Sierra, but it doesn't like it, the system won't boot (that was kind of expected).

I have now ordered an active USB-C to HDMI 2.0 cable, let's see how that goes.
 

kave

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Oct 31, 2012
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During my one year with my 15" TB I found that clamshell mode does not work reliably. I am back on my 11" Air now which works 95% of the time (sometimes it is shut off instead of sleeping etc). External monitor always turns on as it should. I have been using Apples Digital Multiport adapter as well as third party and they all behave the same.
 

ManuCH

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So here's my update: I brought my 15" tMBP at work and used the same USB-C to DisplayPort cable I used with my Asus screen to connect a Dell screen.

Result: it works. So this issue seems to be a specific interop issue between the tMBP and the Asus MX27UC, as other screens work correctly.

I have also updated the Apple bug report with a video, as they requested.

In the meantime I have purchased a Delock 4K@60Hz HDMI cable, which also works using Alternate DisplayPort mode over USB-C. I have connected my Asus screen using this cable and it works properly. I have also added an Elgato Thunderbolt 3 Dock to the mix, so I can again use 1 cable only for both video and charging.

In other words, as a workaround for some weird Radeon driver bug I had to shell out another $350 to have a working system. Not happy to be honest.
 
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bartvk

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Weird... it's a shame, it looks like a nice screen. Thanks for updating this topic, very useful info for anyone looking for a 4K screen.
 

networksplus

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Oct 12, 2017
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So here's my update: I brought my 15" tMBP at work and used the same USB-C to DisplayPort cable I used with my Asus screen to connect a Dell screen.

Result: it works. So this issue seems to be a specific interop issue between the tMBP and the Asus MX27UC, as other screens work correctly.

I have also updated the Apple bug report with a video, as they requested.

In the meantime I have purchased a Delock 4K@60Hz HDMI cable, which also works using Alternate DisplayPort mode over USB-C. I have connected my Asus screen using this cable and it works properly. I have also added an Elgato Thunderbolt 3 Dock to the mix, so I can again use 1 cable only for both video and charging.

In other words, as a workaround for some weird Radeon driver bug I had to shell out another $350 to have a working system. Not happy to be honest.


I was so glad to find this thread! I started having this issue today when I upgraded my 2017 MBP to High Sierra. I have a pair of Acer H277KH 4K monitors. Same exact issue. USB-C connected monitors work after you boot up until it goes to sleep! I hope Apple is looking into this!
 

ManuCH

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Weird... it's a shame, it looks like a nice screen. Thanks for updating this topic, very useful info for anyone looking for a 4K screen.
It's a nice screen indeed. I'm now using it successfully via HDMI while I wait for an Apple fix.

I could also try contacting Asus but I'm afraid that will be a bit of a nightmare...
 

ManuCH

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Seriously, this is crazy: none of the macOS 10.13.1 versions fixed this (including the final release), and now I'm on 10.13.2 beta 1 - still not fixed.

How else do I get Apple's attention? They closed my bug report as a duplicate, without fixing it.
 

jerryk

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Nov 3, 2011
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Seriously, this is crazy: none of the macOS 10.13.1 versions fixed this (including the final release), and now I'm on 10.13.2 beta 1 - still not fixed.

How else do I get Apple's attention? They closed my bug report as a duplicate, without fixing it.
I would not read too much into closing the bug as a dup. I do this all the time at places I work. Duplicate means just that. You want to attach any documentation of any fix you do to one, and only one place.

And is not working on a specific monitor an Apple problem? Seems to be a monitor issue since other monitors work.
 

ManuCH

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And is not working on a specific monitor an Apple problem? Seems to be a monitor issue since other monitors work.
I would agree, had it never worked before. However it works on Sierra, and doesn't work on High Sierra, since they updated the Radeon display driver.

One could argue that Asus and Acer need to update their displays to work with the new Radeon drivers, but it certainly sounds fishy if a display that previously works suddenly stops working.

Yes, I do have a workaround in place (using HDMI), but working IT myself, I hate workarounds, especially if they tend to become a permanent fix :)
 

friednoodles

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Feb 4, 2014
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I wouldn't be surprised if it's related to the other problems people are experiencing with Radeon Pro GPUs in both 2016 and 2017 MBPs in High Sierra after sleep. I and others are experiencing a different issue where, after sleeping, Radeon GPU performance is terrible:

https://forums.macrumors.com/threads/2017-mbp-15-radeon-gpu-does-not-work-after-resume-from-long-sleep.2076334/

Like with your issue, the issue doesn't happen in Sierra and only started with High Sierra. It's incredibly frustrating. My radar about it from September is open with no response.
 

jerryk

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Nov 3, 2011
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I would agree, had it never worked before. However it works on Sierra, and doesn't work on High Sierra, since they updated the Radeon display driver.

One could argue that Asus and Acer need to update their displays to work with the new Radeon drivers, but it certainly sounds fishy if a display that previously works suddenly stops working.

Yes, I do have a workaround in place (using HDMI), but working IT myself, I hate workarounds, especially if they tend to become a permanent fix :)
OK. Missed the fact that it worked in Sierra. Definitely seems like some that should be fixable.
 

planetf1

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Aug 8, 2014
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I don't see this issue with a 2016 tb 15 and lg 27ud88 4k usb-c display... Though sometimes after sleep the external monitor is blank unless cable replugged
 
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yoavf

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Feb 8, 2018
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@ManuCH I'm suffering from the same exact problem, but reverted to Sierra. Did it get better with the recent High Sierra updates?
 

ManuCH

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May 7, 2009
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@ManuCH I'm suffering from the same exact problem, but reverted to Sierra. Did it get better with the recent High Sierra updates?
No, unfortunately it has remained unchanged throughout all High Sierra updates. I'm extremely unhappy with all this at the moment and I'm afraid I'll have to buy a new screen - which is kind of absurd.
 

yoavf

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Feb 8, 2018
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No, unfortunately it has remained unchanged throughout all High Sierra updates. I'm extremely unhappy with all this at the moment and I'm afraid I'll have to buy a new screen - which is kind of absurd.
Thanks for the update - I agree it's absurd. I'm sticking with Sierra for now, but I'm not sure for how long.
 

doitdada

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Oct 14, 2013
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More people with the problem in this thread
https://discussions.apple.com/message/32847321?ac_cid=tw123456#32847321

Seems like it is the computer, not the screen. All my other computers are compliant using different ports, three different Windows 10 desktops and a MacBook 12 2015 works with 4k@60hz (even though it is not supported by Apple), but the tMBP 2016-2017 seem to all have the problem with sleep and wake issues when connected to an external display, both 13 and 15 inch versions.
 

btownguy

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Jun 18, 2009
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I'm having this issue as well. 2017 15" tMBP with Asus PG279Q monitor. Connected using the Apple USB-C AV adapter (USB-C, HDMI, USB-A).

This is very frustrating. Has anyone installed the Mojave beta and have an update to this issue?
 

yoavf

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Feb 8, 2018
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I'm having this issue as well. 2017 15" tMBP with Asus PG279Q monitor. Connected using the Apple USB-C AV adapter (USB-C, HDMI, USB-A).

This is very frustrating. Has anyone installed the Mojave beta and have an update to this issue?
I've tried the first public beta of Mojave - no improvement :(
 

Smashnet

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Apr 28, 2012
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Same issue here with my 2018 rMBP 15" and a LG 27UD88 connected using USB-C.

Only shutting down the MBP seems to solve the issue until next sleep...
 

yoavf

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Feb 8, 2018
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FWIW I upgraded to a new 13" MBP, and this problem doesn't exist with Mojave.