"Live session user" is indeed shown, selectable and able to login if (just for testing!) UID_MIN is set to 999 in /etc/login.defs and accountsservice and lightdm are restarted.
A proper solution might depend on bug #857651.
"Live session user" is indeed shown, selectable and able to login if (just for testing!) UID_MIN is set to 999 in /etc/login.defs and accountsservice and lightdm are restarted.
A proper solution might depend on bug #857651.