It happened to me today. I'm not 100% sure but it had never happened to me until now and happened after the last update followed by a restart.
Version of indicator-datetime: $ apt-cache policy indicator-datetime indicator-datetime: Instalado: 13.10.0+13.10.20131023.2-0ubuntu1 Candidato: 13.10.0+13.10.20131023.2-0ubuntu1 Tabela de versão: *** 13.10.0+13.10.20131023.2-0ubuntu1 0 500 http://br.archive.ubuntu.com/ubuntu/ saucy-updates/main amd64 Packages 100 /var/lib/dpkg/status 13.10.0+13.10.20131016.2-0ubuntu1 0 500 http://br.archive.ubuntu.com/ubuntu/ saucy/main amd64 Packages The quick fix "killall unity-panel-service" worked for me -- You received this bug notification because you are a member of DX Packages, which is subscribed to indicator-datetime in Ubuntu. Matching subscriptions: dx-packages https://bugs.launchpad.net/bugs/1244285 Title: Date/time sometimes doesn’t appear in menu bar, settings greyed out (Ubuntu 13.10, 14.04) Status in One Hundred Papercuts: Incomplete Status in The Date and Time Indicator: Incomplete Status in “indicator-datetime” package in Ubuntu: Incomplete Bug description: it does not happen often, and when it happens, just a log out and re- log in is enough to restore it. http://askubuntu.com/questions/357266/how-to-show-time-in- ubuntu-13-10/357280 To manage notifications about this bug go to: https://bugs.launchpad.net/hundredpapercuts/+bug/1244285/+subscriptions -- Mailing list: https://launchpad.net/~dx-packages Post to : dx-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~dx-packages More help : https://help.launchpad.net/ListHelp