Oh, I think I see some confusion here. AO3 doesn't have 'genres'; it combines freeformtags and ao3categories (fandom). From the default.ini:
Code:
## AO3 doesn't have anything it calls 'genre'. The adapter used to be
## hardcoded to include the site specific metadata freeformtags &
## ao3categories in the standard metadata field genre. By making it
## configurable, users can change it.
include_in_genre: freeformtags, ao3categories
Does freeformtags have entries?