My monitors.xml has two <configuration> blocks, with the only real difference being that one has <layoutmode>physical</layoutmode> and the second has <layoutmode>logical</layoutmode>. I don’t really think that’d be the issue here though, because if the dummy plug is listed as disabled it shouldn’t be trying to use it anyway…?

I think you’re right in reporting it to the GDM repo, at a minimum someone there will know where to point you towards figuring this out. Maybe the GNOME Mutter repo might be a related stop for this too, seeing that’s the part generating the monitors.xml…

The things that are supposed to be simple are always the bits that suck the most!

Yeah, seems like it should just be working…

You’ve probably already got this covered, but when you created your user monitors.xml config, did you have the dummy plug connected and disabled?

Maybe the config:

• has it included as a monitor and enabled as part of the screen layout
• or possibly doesn’t include it at all, and then GDM just assumes it can/should use it as a new option?

When you copy over your monitor config, are you correcting the ownership/permissions?

The little scriptlet I made to combat a previous nvidia/wayland multi-monitor headache boils down to:

sudo cp $HOME/.config/monitors.xml /var/lib/gdm/.config/
sudo chown gdm:gdm /var/lib/gdm/.config/monitors.xml

Maybe double check if GDM is ignoring wayland as well, I’ve definitely had that happen in the past too.