Since January, my normal media setup at church haas been a 2018 Mac Mini configured with 3 displays-2 identical HD displays (1920 X1020) with an Epson projector as the third. One display is main, one is used for a Propresntor window and the projectors use is obvious. I am using HDMI to connect to all three. This was a very simple plug and play setup that has worked flawlessly until this morning.
Now, the Mini will recognize 2 displays-any two, but only two. I checked and rechecked cables, rebooted, etc. My final troubleshooting attempt:
Plug all three displays in and reboot. It boots up seeing the "Propresentor" display and the projector-it does not recognize the "main" display. I manually told it to "detect displays" with no change. Without touching anything else, I unplugged the HDMI cable from the "ProPresenter" display, which is showing the desktop. Obviously, desktop disappears -and after a few seconds, it sees the "main" display and the desktop appears there.
No, I have not updated to Catalina. Yes, the specs say this will support 3 displays (at up to 4K resolution-I'm only at HD).
What to try next? Nothing comes up on searches-maybe I'm using the wrong terms?