Comment 31 for bug 1822937

Same here, with Nvidia 455.45.01 on Ubuntu 20.04. In fact I've been facing this for years, since 18.04.

The workaround I'm using is to call nvidia-settings via a shell script in Gnome's Startup Applications.

It's a bit annoying because it only applies after you log in, but has the additional benefit that you can execute manually if your monitors get out of sync for some reason (handy if you use a KVM that forces X to re-detect monitors).

You can save your config via nvidia-settings to a separate location, and then extract the exact parameters for each monitor. Here's mine:

# monitor-reset.sh:

sh -c 'nvidia-settings --assign XineramaInfoOrder="USB-C-0" --assign CurrentMetaMode="DP-5: 1920x1200 +0+560, USB-C-0: 2560x1600 +1920+160, HDMI-0: 1920x1200 +4480+0 {rotation=left}"' > /dev/null 2>&1