(address . bug-guix@gnu.org)
The Celluloid package generates it's own icon cache at
share/icons/hicolor/icon-theme.cache. When you install the Celluloid, I
believe this overwrites the profile's icon-theme.cache, which causes
none of the other icons to show up in launchers that use this, for
example gnome shell's application launcher.
Perhaps also it is an issue that the profile's generated files do not
have priority over all the files within all the packages installed to
the profile, i.e. none of the packages should be able to overwrite the
files generated with the profile hooks.