Yeah. 12 was the default value in my Firefox about
:config.
You could save your bookmarks into an html file in $HOME, then delete the $HOME/.mozilla directory tree, then run Firefox, import your bookmarks, and see if the awesome bar started to work.
Advantages: quick and easy.
Disadvantage: might not restore the functionality.
I just made the change to MaxRichResults in three other user accounts' about
:config. It did the trick turning the awesome bar function off so that's useful for those of us that hate that feature.