Maybe buy something like an active HDMI Switch just to make it happy (e.g. I found Vention HDMI Splitter Switch 5 input 1 output HDMI Switcher for $15). Also the specs of the board show a DSI/eDP interface. Maybe there is some kind of cheap adapter/or mini-TFT you could hook up to that.
But let’s see what you find out with tcpdump and take it from there.
Edit: Ahh, google is your friend again… (possibly related, but maybe not)
https://github.com/raspberrypi/firmware/issues/211
https://www.raspberrypi.org/forums/viewtopic.php?t=11259
https://communities.intel.com/thread/76913