I installed the plasma version of Calculate Linux (a great distro!) and set the Swiss locale. This works fine, but when the screen saver is activated it rejects my login and also the login as root.
As a work around I found when I click on the Icon “login as a different user”, I can then chose my userlogin in the drop down menu and only then is my password accepted.
This might be a bug that only manifests in certain locales.