monterey – External monitor no longer recognized

I’ve been running the new version of Monterey without problems since it came out very recently. I have a 2019 MacBook Pro (intel, obviously) and connect an LG monitor via USB-C to DisplayPort. I was using the two monitor configuration for hours on end, including overnight sleep and reboots.

Now this morning, it doesn’t recognize the monitor. I’ve turned off all settings related to sleeping, napping, sleep mode, etc. I’ve rebooted multiple times, and power cycled the display. I’ve gone direct and through a dongle.

In attempting to reset nvram I got the feeling that the computer never really powered off. I tried the shutdown command, a very long press on the power button, and a shell shutdown command. In all cases it goes to a totally black screen but the touchpad still clicks and touching it wakes the computer up. Makes me think it’s not quite powered off.

And since I need to power off to reset nvram and sbc I also am not totally sure that I achieved a reset of those, which in turn might clear the problem.

Any suggestions at all?