macOS Catalina 10.15 Beta and Dell D6000
 

I am running the macOS Catalina 10.15 beta version on my Late-2017 Macbook Air with I7 processor and 8 Gb ram. I have two external LED monitors connected via HDMI. I followed the instructions located in this support article: https://support.displaylink.com/know...ina-10-15-beta

After following the instructions, one monitor comes up and is usable along with my built-in display. The other monitor still displays a black screen with a cursor that moves with the mouse that is not usable.

To make that second monitor work right, I have to go into display preferences and choose the mirror option. Once all screens popped up and "mirror" my built-in display, a setup screen for each monitor pops up, I have to choose the option to "optimize" for my non-working display. Once I do that, I uncheck the "mirror" option and the second monitor works.

I have to do this every single time I dock or reboot the computer. Is this a known issue and is there a fix?

I have exactly the same setup and the same issue. I also had to downgrade to 5.1.1 due to an issue with 5.2 only being stable for a few minutes.

After mirroring and un-mirroring with 5.1.1 all works well on both monitors and the laptop screen (three screens total) but if I un-plug the D6000 I have to repeat the mirroring trick to get the third monitor working.

As a followup, I found that the Catalina update to Beta 10 (Sept 30) resolved this issue for me. I have left my driver at 5.1.1 and now the D6000 acts like it did with Mojave.

I still get the occasional issue, i.e. screens go black for a second after the first five min of use, but it will either come back in a second or two, or I need to re-plug the dock.

So far all day today its been solid.