After update from 10.15.3 to 10.15.4 external displays doesn't work via docking station

You’ll note your posting was moderated.

It it’s fine to post here but you should also consider advice. That’s the real reason for this forum. People helping people. We all vent a bit, but focus on solutions.

If you don’t have IT support, I would again caution you and your organization from upgrading anything widely. Try one machine first and be sure all mission critical functions work before upgrading other machines. And call for support. The issues mentioned here are not easily solved in a forum, beyond the advice already shared, and that apparently has worked for some.

I’ll offer one more suggestion, which you may not want to try. Erase, format and do a completely clean install. Do it on a bootable external if you don’t want to erase your internal. That said, what I’ve seen here is that using different interfaces, hubs, cables results in it working. This suggests to me that it may be a hardware issue, or third party software. Call Apple. Call the manufacturer. Complaing about Apple here isn’t going to solve your problem.

Best of luck.

I wanted to add a couple of new symptoms. If the MBP is closed and the monitor is connected it will power on and give me the log in screen for the encrypted HD on the external display. However, once it starts to load the OS the external screen will go black and not come on again. If I lift the lid on the MBP it will be at the desktop and act like the external monitor is on (extended desktop).

Also, when the CPU usage spikes the external monitor will go black, come back on, go black and then come back on.

All of this behavior is post 10.15.4 install.

For what it is worth the System Profiler shows both displays connected to the Radeon Pro 5300M on my 2019 16" MBP.

It also shows the chip set in the HP USB-C G5 Dock as Microchip Tech. But that could just be on the USB 3.1 and PD side of things.

And lastly, once I do get it working through various fidgeting (mostly plugin, unplug, plugin, unplug, plugin...until it works) if I put the laptop to Sleep rather than Shut Down it will reliably start the external monitor on wake. I have done this over a couple of days now. So, there is just some disconnect when the OS (drivers?) loads at start up. And the weird screen flicker at high loads.

I have also come to realize that the dock is no longer charging the battery. The System Profiler shows that the power supply is connected and delivering 75 Watts. But it will not show as charging. The 96W adapter from Apple works fine plugged in to another port. So, may be a USB-C PD negotiation problem post update.

Just wanted to add a few more details incase anyone at Apple is following. :-)

I think that was what solved it for me (MP), usb-c dongle by Apple (usb-c to (1xusb-c, HDMI, USB)), tried everything and just switching to (in my case) usb-c port closest to the lid-end solved it. Funny thing is, now the the original port I was using works as well, go figure....

I have a 16 inch MacBook Pro. In the end I’ve just given up and bought the Apple equivalent.

i can confirm it works with the Apple USB c device and failed with my alogic USB c device. A real shame but I had to keep working.

I had call with someone from AppleCare, we made some diagnostics with my MacBook 16" with 10.15.4 and MacBook Pro 13" 10.15.3 that is working fine.

So they know it is bug relating to last update. So I hope it will be fixed ASAP.

Please report this issue to the Apple support assistant. That might be a much better way to inform Apple about this issue. You can visit this website (https://getsupport.apple.com/?caller=psp&PRKEYS=PL107 ) and make a case. This forum is not a good place to let them know. 

My case number is 101053644789. If anyone had reported the case number, please share those case numbers here as well. Collectively, we can show that it’s not a mishap or this-Mac-only problem. 

I have been able to replicate the issue through 3 different cables and 1 dock.

For some reason if you leave the Macbook Pro open, my screen works fine. If I close the MacBook Pro, then within 5 minutes the screen goes black. additionally I can't get the screen to come on with moving the external trackpad or keyboard, which I was able to do on version 10.15.3

I would suggest submitting the issue with details to apple here: https://www.apple.com/feedback/macos.html

I have been trying to find a way to do this too. The best options I have seen are doing a restore from a Time Machine Backup before the update, which is a royal pain. The other option is to completely wipe the computer and install a 10.15.3 version... even less fun.

I did go to Alogic website, this is the dock I am using, https://www.alogic.co/catalog/product/view/id/4032/s/alogic-usb-c-dock-plus-with-power-delivery-ultra-series-silver/category/262/

they don't have any section to update the firmware, and this dongle was working fine before I upgrade to 10.15.4.

Initially, I thought it's either the dock, the cable or the monitor. After I tried to use the dongle on a different laptop, the dongle works fine. So it's not the cable, the monitor and the dock. Hopefully Apple is not upgrading its OS to force user to buy they own accessories (like what their did to the iphone cables).

After reading Apple's MacOs releasing note here https://support.apple.com/en-au/HT210642, in the bug fixes section, they have made some changes to the display side things. Which make me feel my issue is kind of related to this update.

This issue is not exclusive to users using docking stations or hubs. I have a DisplayPort monitor connected with a USB-C to DisplayPort cable: in 10.15.3 it works, in 10.15.4 it does not.

Trying to deny this issue is caused by the software update, or trying to incorrectly suggest Apple never ships bugs frankly isn’t helpful. I’ve personally filed radars for bugs in beta versions in macOS that have still been shipped in the final version. Apple’s feedback tools for developers are poor.

If Apple’s standards have changed as you suggest without evidence, it would be incumbent on Apple to publish those changes.

Judging from 10.15.4’s release notes, the release included changes to support for HDR displays over DisplayPort and HDMI. The most reasonable explanation is that these changes resulted in bugs that have negatively affected users of some external displays.

Apple really has grudge on Dell.

Do this step by step.

a) Pre-requisites, have your devices unplugged and power-off. Avoid plugging it in, until you have done the “full SMC reset”, I did it twice, before I try only doing the partial step. Up till the 10 sec power button hold.

b) With the devices still unplugged. Login Mac.

c) Then power-on devices and plug them in with your Security & Privacy settings opened. Watch for anything that might pop up or appear asking for permission. worry it’s a bug on different types of devices / drives when you start to connect them one by one - gradually.

if all else fail, call Apple. :D

Just an FYI. I purchased a StarTech TB3DK2DHV Dock. It uses a 40GPS Thunderbolt 3 cable to connect the computer to the dock and supports 2 4K monitors at 60Hz. It is working correctly as of now plugged into a Dell P2715Q 4K monitor and with the lid shut, the screen stays on. I am also able to wake the computer form sleep with the external keyboard or trackpad.

I had multiple USB-C to HDMI cables, and with the update, they still aren't working and the Mac stays on for a few minutes with the lid shut and then goes to sleep.

Blndvs wrote:

Okay so I just switched to this found on Amazon -

USB C Hub, USB C Docking Station, QGeeM 12 in 1 Triple Display Type C Hub to Dual 4K HDMI & DP,USB C to USB Adapter,100W PD, Gigabit Ethernet, USB C Card Reader,USB Docking Station

It's money spent, but works perfectly and much smaller than the old D7000 I was using, plus portable.

Hope this helps anyone open to the idea of purchasing a new dock.

So, why does one item work and another does not??? Apple is not the only variable here. Granted, changes to the OS have identified problems in some hubs, but again, if this was widespread, it would be all over the internet. Trouble shoot. Cables, Firmware. A different hub. SMC reset. Sorry but this kind of stuff happens on all computers. And what works for one person is not always going to work for another, because there are too many variables between each. Sorry, but obviously the vast majority of folks are not having these issues. I feel bad but troubleshooting is part of the processs.

Don't upgrade until you back up, and test changes before you are committed. Get a backup drive you can use to restore if needed.

And beware buying whatever is cheap at Amazon. Apple sells these two which suggests they work fine:

Belkin Thunderbolt 3 Express Dock HD

CalDigit TS3 Plus Dock

They are no less at Amazon (at not least with a quick look).

@Hendrixwb Long long list of HDMI issues on MAC Mini that started with Catalina over here.

For myself, i've had the same dock for a number of years. I have 2 equivalent MBP and a MB Air. My issues with Apple and external monitors started with the supplementary patch update to 10.14.6. As such one of my MBP is still on 10.14.5. On 10.14.6 the windowserver process went high cpu if you had an external monitor connected to the MBP and nightshift was enabled. After performing low level detailed anayltics on the issue with apple engineers for a few weeks they said that it would be fixed in catalina. Catalina bricked my mac altogether but when it was fixed after 2 weeks the initial issue was fixed but now it had another issue. On 10.15.1 if you connect and disconnect a monitor connected to the dock the MACOS itself adjusts to the incorrect resolution on re-connection and selects a much lower resolution. You can use ACGDianose and see that the MACOS has switched to low bandwidth HBR instead of HBR2. If i use the MBP that is still on 10.14.5 it works perfectly without a issue at all. While I would like to upgrade to see if it fixes my issues there is the possibility that it gets worse. And upgrading at present seems to result in changing the firmware on multiple items that seem to result in failures of the machine from various reports across the board. Apple have now also made it impossible to take the firmware backwards unless you completely reinstall from scratch (and I am not sure that will). If you don't take the firmware backwards there is a efidiagnose or check program that runs via cron from memory that tells you that your bios is corrupt.

So, all things considered for myself, its safer to stay put and never upgrade unless it becomes critically essential. Forget new features from Apple and stay at a release where things are working with manual intervention rather than take the risk. Especially when you are in lock down.

Simple Apple have lost the ability to marry the MACOS hardware and Software together which has been demonstrated across Catalina. Just turn off auto update altogether and mange your decisions yoruself if you want your MAC to work.

Ready through the earlier post on page 9 - 15.

I have fixed problem with my dock. Turns out my NAS connected directly via Thunderbolt 3.

Also need to do SMC reset twice with everything unplugged front MBP