Have the same problem. It's not keyboard, or gdm config. You have to edit pam.d config.
as root edit file
nano /etc/pam.d/gdm-password
find line
auth required pam_succeed_if.so user != root...
Type: Posts; User: botul
Have the same problem. It's not keyboard, or gdm config. You have to edit pam.d config.
as root edit file
nano /etc/pam.d/gdm-password
find line
auth required pam_succeed_if.so user != root...