If I were you, I would send a ticket to KingsIsle, they can help. If you don't wanna wait that long, try doing the arena battle again or just realm hop and see if that works. Good luck!
Yeah, a ticket might be a good idea. Realm hopping too.
However, there is no "doing battle arena again", as I never got that quest in the first place. I did Pixelles' quest and there was nothing after. He sent me no nowhere and to no one. I only know that a quest was supposed to come after because I looked it up.