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

I have Lenovo USB-C 6-in-1, HDMI to my LG 4k TV doesn't work correctly anymore (Picture isn't showing on the whole screen, no matter what resolution I choose. Worked just fine on 10.5.3), and apparently moving files from USB sticks somehow broke as well. It only transfers first 1-5 gigs and then just gets stuck, until I remove the stick.

EDIT: Display problem was corrected with SMC reset.

Please report this issue to Apple by calling to the support team(https://getsupport.apple.com/?caller=psp&PRKEYS=PL107).

This community isn't that helpful to escalate the issue to Apple.

Last week, I made a call to Apple and the staff requested to connect to my Mac to find the problem. With all the suggested instructions including resetting SMC, NVRAM, he concluded that he needed to report this issue to the relevant team. To do so, I needed to support him—by taking several photos of the monitor by showing that it's working fine with another mac and also running a couple of programs to collect logs on my Mac. I uploaded those to the website link which was in the email from the same staff. Overall, it took me more than 30 mins.

If people with similar problems report the same issue, Apple will eventually know that their recent update has some relevant issue. I think this could be one of the most effective ways to let them know/solve the problem.

For anyone who likes to report this issue to Apple via care support, let them know similar case numbers:

* MBP 16 inch+Dell UP2414Q(4k 60hz) dp1.2 to usb c broken (@Kei Kim case 101053644789)

* MBP 16 inch+Icy box DK-2403-C docking station (@Weber_NRW case 101056259745)

And also please share your case number & setup. 

Thanks.

Hi.

Dont need the full SMC rest. Just use the following for MBP with T2 Chip

• Unplug all cables or anything connecting to Mac 💻
• Shutdown MacOS
• Hold power off button for 10 sec. Then release
• Wait a few seconds. Then power on Macbook

https://support.apple.com/en-us/HT201295

Keep all the ports unplugged. What happens next is crucial.

• login check on System Preferences —> Security & Privacy, you may need to give permission to the devices or drivers.
• plug in your devices. give the devices to connect via Security & Privacy permission.

Works fine now.

Make sure when you plug in first device to a dock nothing else with Thunderbolt is connected to it I never have to do anything finally. just unplug the Thunderbolt3 connected to my dock then reboot. and connect dock without the Thunderbolt devices to it.

Hi joãofromevora,

The only way works for me right now is the method provided by gvfx2000. Does that work for you?

Normally I would first set "Turn display off after" 1min in Energy Saver of Syestem Preferences. Then connect the external monitor and wait over 1min until the macbook internal display is off. Then wake up the computer and the external display would work perfectly.

Then, I will set the "Turn display off after" to "Never" or a very long time, because if the display turns off and on again, sometimes the computer would restart for no reason and you will lose all unsaved data.

Also, once for a while, the external monitor would just work without going through the above procedure. But this is not stable. After some time, I need to go through the procedure again.

Hope this helps.

CalDigit Thunderbolt 3 Mini Dock for connecting 2 External Monitors for Mac Book Pro

Extending Displays was not working when I was docking my new Mac Book Pro 2020 on Catalina 10.15.5. I was using one USB C for power and one USB C for an adapter. With two external displays (not using the Mac Book's display) it was only mirroring the displays and did not recognize two external displays. The adapter was made by Monodeals. I bought the CalDigit Thunderbolt 3 Mini Dock. Yes, way more expensive - but it works correctly now.

Like many of the others that called support - they seemed to be unaware of this issue. Thanks for posting about the CalDigit adapter.

Hello, after over a month of trial and error, here is what works for me and saves me a lot of time.

My setup: MacBook Pro 16 inch, Sharp 32-inch 4K LCD monitor (bought in 2014), USB-C to DisplayPort cable (any brand is OK).

1. Before connecting the monitor, open System Preferences and change "Turn display off after" to "1 min". Also (this is very important), uncheck "Prevent computer from sleeping automatically when the display is off". You need the computer to go to sleep as soon as possible.
2. Connecting the external monitor, the display on your MacBook Pro should have some change indicating the external monitor is recognized by the computer. For example, all the files on the MacBook desktop will disappear because they are now on the external monitor, even thought the external monitor is still not active right now.
3. Wait for the computer to go to sleep in about 2 minutes. To make sure the computer is indeed sleeping, you can connect an external drive that has a LED indicator. When the LED on the external drive is off, the computer is surely sleeping.
4. Wake up the computer, the external monitor should be active.
5. Open System Preferences and change "Turn display off after" to "Never". You can setup a "Screen Savor" to protect your monitors.
6. In my case, if I don't shut down or restart my computer or turn off the power of the external monitor, the external monitor works perfectly without the need to repeat Step1-5. But sometime without any reason, the connection is broken again, and Step 1-5 should be repeated.

Hope this is useful. It's still annoying but waiting for 2 minutes to get the external monitor working is OK for me.

I had a similar problem when my MacBook Por updated to 10.15.4 and I solved it just by unplugging and exchanging usb-c ports between devices.

Best of luck to you all.

I had similar issues. Resetting the SMC worked for me. 2019 MacBook Pro 13”

Based on a thread here, I reversed the type c ports on my docking adapter by simply connecting the docking adapter upside down so that the ports switched. No it works....

A supplemental update to Catalina has just been released. Have you tried?

Try the full SMC Reset from the Apple Official guide. The extended steps after the 10 sec power button hold.

I have the same problem, today I decided to make a clean install of macos 10.15.4 and my two external displays connected to a dock dell D6000 don’t work. The main display start blinking while it’s connected to the dock and the external displays don’t show anything.

I tried the latest drivers from displaylink but it didn’t work... Maybe a fast solution is to make a downgrade to the 10.15.3

After updating to 10.15.4, my external monitor Dell UP2414Q which uses Display Port 1.2 stopped working. I don't use a docking station, but my issue must be a relevant problem. When I dropped the connection to 1.1a in the menu, the OS is able to display the screen at 4k@30hz. Prior to this version, in 10.15.3, the monitor worked just fine.