Portable monitor on Mac Mini not detected I purchased a Zenscreen monitor recently from Asus so I can travel with my Mac mini. This screen connects via USB-C. The problem is that it isn't automatically detected unless another monitor is connected to the Mac Mini. I have tried every single port on the back of the Mac. I have turned it on and off again.

I have tried different cables. But the only thing that will turn the Zenscreen on is by plugging my larger monitor into the HDMI port. The mac immediately detects both monitors and at this point I can unplug the larger monitor and the Zenscreen will stay powered on and functional.

Is there anything I can do differently? I don't think it's the Zenscreen because it works with my windows laptop just fine. But then again, it has a monitor built in so it's not really the same situation.
I have had the same problem. I just upgraded to Catalina. I also updated my zen screen to the Catalina upload on the display link website.  My monitor now starts when I start my mini Mac. However, I must make sure I turn off my Asus display when I shut down the computer, if I don’t Shut down the monitor it won’t start when I restart my mini Mac.