The reason was two-fold.
Canelo and GGG couldn’t come to an agreement on fighting a third time. Canelo wanted the fight to be similar to the first two in Vegas and GGG didn’t want to fight in Vegas because he felt he got a raw deal on the last two decisions.
Furthermore, Canelo felt the business with GGG was done.
Secondly, DAZN would only approve Canelo to fight GGG or Sergey Kovalev, but Kovalev, because he had a fight already scheduled, was demanding at least the same amount of money that Daniel Jacobs got for fighting Canelo.
To make the fight happen Kovalev was going to have to pay a lot of step aside money to a lot of people before he got any money himself.
So, the compromise was for Canelo not to fight in September, let Kovalev fight his upcoming fight and try to make the fight for December (it is also possible GGG could be that opponent).
Flip the page for Golden Boy’s statement on the matter and why Canelo feels he won the GGG fights.