There’s nothing to fix as Mirage-Raceway is on the same cluster as the only other destination, Pyrewood Village. Therefore transfers are not available at this time.
You can see an example of a previous player here having the same problem but with Golemagg to Firemaw: Golemagg Has free character transfer that doesn't work - #2 by Saneko-ragnaros
Edit: The above is for Classic WoW and may be inaccurate for Progression Classic.