The url should have the tag "workout au".
Regardless, I figured out the issue.
it was actually the second line of code, made worse by the first. Anytime the second line ran into "Alternate Universe", it would run creating the blank "AU:". So I changed it to this and it worked:
Code:
genre=>(.*) [Aa][Uu](|!)=>Alternate Universe,AU: \1
genre=>(Alternate Universe)( - )?(.+)=>\1,AU: \3
Thanks for the help. Your suggestions helped me think of alternatives.