Comment # 7 on bug 936979 from Stefan Hundhammer

When started from the YaST control center, this line is executed:

https://github.com/yast/yast-packager/blob/master/desktop/yast2-packager.desktop#L5

    xdg-su -c "/sbin/yast2 sw_single

This should open a password dialog to query for the root password.
Does this work for you?
Does a simple command with xdg-su work for you? E.g.

    xgd-su -c "ls /root"

Please check.