Connecting to a computer with no active monitor
Hmm, that seemed to work. It seems running the screen directly to the mini PC, and unplugging it from the HDMI connector leaves the desktop on as intended.
I was trying it running the monitor through a docking station and connected through the USB port to the mini PC, and that didn't work very well when I disconnected the docking station from the mini PC.
I guess you're right about the signal not beeing correctly.
( I was already running unattended )