Check in /etc/X11 for the existence of the xorg.conf file.
I experienced this problem with Nanjaro/Gnome, using Wayland with an Nvidia GPU and the proprietary driver. Spelunking around revealed there was no xorg.conf file in /etc/X11.
My fix was to log out of the Wayland session, log back in with an X.org session (click on the little gear in the lower right corner on the password screen to open options), select Gnome on X.org and then enter my user password where indicated.
The session came up normally using X.Org as the display manager.
Once there, I opened the Nvidia setting application (does not work in Wayland), clicked on the “X Server Display Configuration” selection, clicked on the “save to X configuration file” option. Didn’t make any changes to configuration.
Closed the Nvidia application, logged out of the X.org session and at this time selected the “Gnome” option from the password entry screen. The Wayland session opened normally and I haven’t experienced the blank login /GDM failed to start on boot issue since.