WWE initially showed interest in bringing Mysterio back in order to serve as a ambassador to the Latin American market, along with Global Force Wrestling (GFW) who also showed heavy interest in getting their hands on the former Lucha Underground star.
The report suggests, however, that WWE has decided to pass on Mysterio due to McMahon's issues with his representation - Konnan. The issues stem back a few decades when McMahon invested a ton of time and money into Konnan's "Max Moon" character, before Konnan ultimately made the decision to go serve as a main eventer in Mexico. Konnan was even at a recent taping of SmackDown Live to visit Chris Jericho,but the visit did nothing to help mend his relationship with McMahon or the company.
It is now expected that Mysterio will receive an enticing offer from GFW where, if signed, he'd serve as the company's biggest star.