The normal means for shutting down by using panel action button/Shutdown or application menu/Logout/Shutdown fail without any entry in journal, although the usual 30 second message is displayed.
Shutting down using
alias poff='sudo poweroff') from terminal does work.
xfce 4.14 but also occurred with earlier release
Update: since this is a remote (off site) system using the normal means for shutting down avoids a huge inconvenience.
In any case, have a standard feature of the Desktop environment not work can portend other problems.