Hello,
I suffered similar issue 2 times recently (acer monitor not recognized on HDMI).
It was working, then I switched some USB devices and the monitor went off.
It was very hard to wake it up but I did, finally.
I cannot tell you if this will work, but probably I did something as: unplug USB-C/HDMI adapter,
close the computer (screen) to make it sleep,
plug the adapter,
open the computer.
Screen was recognized but I won't try again to make sure that the above works. :)
Regards
buszu
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution