Comment 19 for bug 1546328

@Ross: The difference between Debian and Xubuntu is that the latter has an indicators-based tray, so Qt tries to use that too.

Anyway, have you tested if the bug still occurs with the latest qtbase upload? If that is the case, I will try to look at it.

As a temporary workaround, try installing appmenu-qt5 package (after logout/login the bug should be gone).