Catalina Beta 6 and 7 Killed my 4k external monitor

[xwickx]

Not sure if anyone else had this happen but after installing the latest build (10.15 Beta (19A546d)) - my 4K external monitor stopped working, it was working just fine prior to the installation. I have a MacBook 12" early 2015. I am using apple adapters, and have tried different monitors/TVs and different adapters. I have found that it works fine on: LG ultrawide monitor, 1080p TVs

but it doesn't detect the display for: LG 4K monitor, 4K TVs, and a Projector (not sure the resolution on that)

I tried "detect displays" from system preferences but it still doesn't work.

I updated with today's Beta release but still nothing. Is anyone else having this problem?

 

[mmomega]

Not having the same issues.
I have 3 - 4K monitors on 3 different machines, all on catalina, all still working.
No adapters.
1 connected over USB-C on iMac Pro
1 connected over DP from eGPU on 2018 Mac Mini
Another connected over DP from eGPU on another 2018 Mac Mini

Hope you get it figured out.

 

[EgbertAttrick]

Not sure if anyone else had this happen but after installing the latest build (10.15 Beta (19A546d)) - my 4K external monitor stopped working, it was working just fine prior to the installation. I have a MacBook 12" early 2015. I am using apple adapters, and have tried different monitors/TVs and different adapters. I have found that it works fine on: LG ultrawide monitor, 1080p TVs

but it doesn't detect the display for: LG 4K monitor, 4K TVs, and a Projector (not sure the resolution on that)

I tried "detect displays" from system preferences but it still doesn't work.

I updated with today's Beta release but still nothing. Is anyone else having this problem?

Similar, but not exact.

My MBP outputs to the display, but doe not detect it otherwise. I cannot put audio through my LG UltraFine 4k, and I cannot adjust the display brightness.

 

[EgbertAttrick]

I solved the problem but powering down both the MBP and display, unplugged the display, and restarted everything. All is A-OK, now.