display blinks 27" after update 10.14.6

Are you by any chance in Safe mode? Safe mode uses more conservative video drivers and it will sometimes show refresh lines as it updates the screen

Verify Safe mode via Applications -> Utilities -> System Information -> Software -> Boot Mode -> Safe vs Normal

˜What all 3rd party extensions are you running?

EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac.

http://www.etresoft.com/etrecheck

Pastebin is a good place to paste the whole report...

https://pastebin.com/

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck.

What brand & what type of cable/adapter?

Hey Christer 33,

I have the same problem with a different USB C HUB - I accually did go buy a new screen, and bourght a DISPLAY PORT to MINI DISPLAY PORT adaptor to it. This screen also did the same. It was a 4K philips monitor.

It blinks every 8-15 seconds.

How am we suppose to connect a screen now, when the mac book dosent have any other conenctors than USB-C, and almost every screen comes with HDMI or/and display port.

Simon

Whew that's terrible news from Apple. :(

I have the same problem with a different USB C HUB - I accually did go buy a new screen, and bourght a DISPLAY PORT to MINI DISPLAY PORT adaptor to it. This screen also did the same. It was a 4K philips monitor.

If you have a USB-C based Mac, how do you attach a mini Display Port to DisplayPort to this Mac?

I have a USB-C based Mac and I use a Thunderbolt 3 dock attached via a USB-C port on the Mac, where the Dock provides things like HDMI, Ethernet, USB3 ports, etc... There are Thunderbolt 3 docks that have all manor of video ports available.

If you just want a USB-C to HDMI cable, you can get those. As well as USB-C to DisplayPort.

We have a guy at work using a Toshiba Thunderbolt 3 dock to drive 2 4K Dell monitors via a single USB-C connection which is also providing power to his Macbook Pro.