5. Authentication Logging
Authentication logging can be very useful to look at if you are having issues logging in.
This contains system authorization logs, such as user login and the authentication method used.
Jan 31 10:37:50 icebox pkexec: pam_unix(polkit-1:session): session opened for user root by (uid=1000)
Do some failed logins and then a successful one, look at your /var/log/auth.log and see what happened.
What log is used for user authentication?