My laptop is an Ubuntu install which I use with the laptop's monitor + an additional display which I plug / unplug with a HDMI extension cable. Everything was working fine until just recently.
1. Upon plugging in the HDMI cable, we find 3 displays, of which the 2nd is one that does not exist:
2. I use the Display Settings app to remove the erroneous display. So far so good!
3. I then assign primary display, and adjust the alignment relation of the monitors:
4. Upon clicking "Apply", suddenly only the HDMI display remains, and the laptop display switches off:
5. Alternatively, it jumps back to the original setup, with an erroneous "No# 2" display.
I'm not sure what causes one behaviour over another. Sometimes unplugging + replugging works. Sometimes a reboot works. Sometimes reboot works if HDMI is unplugged at time of reboot. Sometimes I can get the display settings to respond to the app and it doesn't reset - but I'm not sure the exact incantation to make it happen every time.
Either way, it used to all work, and suddenly it no longer does. I don't have any suspect in terms of a hardware or software change just prior.
From neofetch:
OS: Ubuntu 22.04.4 LTS x86_64
Kernel: 6.8.0-40-generic
Packages: 2717 (dpkg), 26 (snap)
Shell: bash 5.1.16
Resolution: 1920x1080, 1920x1080
DE: GNOME 42.9
WM: Mutter
WM Theme: Adwaita
Terminal: gnome-terminal
