Multiseat issue: Can only log in once on second seat.

[n17r4m]

I have a 2-seat, multi-nividia-gpu system that has been working pretty great for a while that was configured using loginctl (systemd). It's a pretty conventional systemd / gnome install.

Unfortunately, for the past two months or so a new behavior has emerged (no pun intended) where on the second seat (seat1) everything works fine on first login through GDM, but after logging out the screen immediately goes to sleep, and it won't wake back up.

A reboot or "systemctl restart gdm" fixes it, but this is disruptive to other users on the system. (This in in a university lab).

The primary seat (seat0) has no issues. It kind of feels like Xorg or GDM is quitting after logout on seat1 and so there is nothing to display. All the logs look pretty normal, no errors..

I know multi-seat configs are pretty rare in the wild, but just maybe someone is around here with experience and can point me in a direction of things to look for. As far as I can tell, Xorg / GDM is not resetting itself correctly to take control again of the seat1 display, but I'm sort of at a loss on where to begin debugging / fixing this issue. Thanks in advance to any one that can offer a bit of help!