User blog comment:FairyRaven/Fairy Tail Chapter 421: Wendy and Chelia, Review and Commentary/@comment-24039250-20150224014538/@comment-3285005-20150224092854

@Nick, yeah they never mentioned that, though they also never mentioned how Asuka was able to see her.

My theory for Asuka's case is because of her parents being members of Fairy Tail and that she's really close to the guild, Mavis was able to let her see her like the other members can.