There is a fix for this issue in KDE Applications 16.08.1 (see https://cgit.kde.org/kdepim.git/commit/?h=Applications/16.08&id=cc2d8bb39417b186bfe40470eba921a64ef6c6c8)
Adding OnlyShowIn=KDE is the wrong solution, since that could prevent KAlarm from starting even when the user wants to use it under Gnome or other desktops. -- David Jarvie. KDE developer. KAlarm author -- http://www.astrojar.org.uk/kalarm
