
This is due to an entry in the “gnome*panel*.desktop” files located in “/usr/share/applications”:
OnlyShowIn=GNOME;
You can quickly fix this by changing it to:
OnlyShowIn=GNOME;Awesome;
Of course you do not have to do this by hand. Simply use this handy command:
sudo find /usr/share/applications/ -name "gnome*panel*desktop" -print | xargs sudo sed -i 's/OnlyShowIn=GNOME;/OnlyShowIn=GNOME;Awesome;/g'