In rawhide, GNOME menus no long include /usr/share/control-center-2.0 so gnome-im-properties.desktop should be installed in /usr/share/applications. (If you only want it in the GNOME menus, add "OnlyShowIn=GNOME;") I fixed this upsteam, so probably just need to update to latest upstream version.
s/gnome-im-properties/gnome-volume-properties/ obviously :-)