Pius XII didn't fulfill the requirements for the Consecration. The bishops of the world did not simultaneously consecrate Russia to the Immaculate Heart, which is something Our Lady requested as a part of this Consecration. There was no solemn act of reparation for the sins of Russia, which Our Lady gave as another requirement for the Consecration. Also, he consecrated the peoples of Russia, even though Our Lady specifically requested the consecration of the nation of Russia. These conditions were not met, which is why this particular consecration did not bring about the miraculous results promised by the Blessed Virgin Mary that were attached to the specific consecration she requested.