Comment # 29 on bug 846914 from Karl Cheng

Different systems have different use cases. At least for Leap 15.x, this should
be an issue with polkit policy. If you wish to enable this, you can change the
policy using the instructions here:
https://unix.stackexchange.com/questions/289123/explanation-of-file-org-freedesktop-login1-policy

To check if this is the case, you can create a file at the following location:
/etc/polkit-1/rules.d/99-hibernate-multiuser.rules

polkit.addRule(function(action, subject) {
   if ((action.id == "org.freedesktop.login1.hibernate-multiple-sessions")) {
      return polkit.Result.YES;
   }
});