What I meant to say is that I don’t use branch 15 since a while.
However at https://demo.tiki.org/15x/tiki-adminusers.php it is ok.
Also this is a critical problem and it is unlikely there is a bug there and no one saw it.
Look to me like something in your own Tiki (install, server, etc).
Something we could test ?
... May be for the next Tiki Open Office Hour ?