Copying Olivier's comment from upstream bug: I was able to locate the problem. The problem is in ubuntu's "appmenu- qt5" and is a bug that cause our call to QSystemTrayIcon::isSystemTrayAvailable() to remove the icon.
That's because appmenu-qt5 seems to assume there is only one QPlatformSystemTrayIcon while there can be one per QSystemTrayIcon. in particular, QSystemTrayIcon::isSystemTrayAvailable creates a temporary one, and when it gets distroyed, it unregister the dbus object for the existing systray. Adding the appmenu-qt5 task accordingly. ** Also affects: appmenu-qt5 (Ubuntu) Importance: Undecided Status: New ** Changed in: appmenu-qt5 (Ubuntu) Importance: Undecided => High ** Changed in: appmenu-qt5 (Ubuntu) Status: New => Triaged -- You received this bug notification because you are a member of DX Packages, which is subscribed to appmenu-qt5 in Ubuntu. https://bugs.launchpad.net/bugs/1573639 Title: ownCloud Client system tray icon integration broken Status in appmenu-qt5 package in Ubuntu: Triaged Status in owncloud-client package in Ubuntu: Confirmed Bug description: The ownCloud client in Xenial is compiled against Qt 5.5.1. when starting the client, the system tray icon does not show up, making the application essentially useless. See also: https://github.com/owncloud/client/issues/4693. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/appmenu-qt5/+bug/1573639/+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