NIS users do not show up on the login screen, only local users. NIS seems to be configured correctly, though. ypcat passwd works fine and I can login on a NIS user account using “su username”.
What happens if you choose a different login screen theme that allows you to type in any user name? E.g. Elarun for SDDM.
Probably still not supported … https://forums.opensuse.org/showthread.php/508724-SDDM-not-supporting-NIS-(yellowpages)-accounts
I used kdm and that works fine.
Thanks,
Aldo