I recently upgraded to 20.04 using sudo do-release-upgrade -d and I ran into some issues with my setup. Previously with 18.04 I was able to work with a multiseat setup using loginctl attach seatx [insert devices here]. I have multiple video cards which I thought I could use to set up separate sessions, but it seems to have been broken. I think this might have to do with the video card settings, as I have a Radeon 6670 and Nvidia GTX 1050 Ti. If I try logging in multiple users, I can only see the session from one video card at a time and the other user is booted off. I tried changing the grub config nouveau.modeset but that didn’t help. I tried using nouveau over the NVIDIA drivers, and couldn’t get multiseat working either.