Why won’t my Sylveon pass down its Hidden Ability?

Question

In Pokémon Sword, I have my HA male Sylveon and I got it in a trade so it’s Korean, I tried breeding it with a ditto but it won’t pass on it’s hidden ability, can someone please explain why?

Answer 1

In all games where Sylveon is present, male Pokemon have a 60% chance to pass down their HA when bred with Ditto. If it hasn't happened yet, simply continue breeding and you will eventually hatch a HA Eevee. There is no possible reason that this would not work except for bad luck.

Two potential sources of confusion are:

1. Eevee's HA is Anticipation, not Pixilate. When you get an Eevee with Anticipation, it has successfully inherited Sylveon's HA slot. It will evolve into a Pixilate Sylveon (or any other Eeveelution with its HA).
2. Anticipation is visually similar to one of Eevee's regular abilities, Adaptability. Take care not to confuse the two.

Answer 2

Since Generation VI, it is possible for male and gender-unknown Pokémon (such as Magnemite) to pass down their Ability if bred with a Ditto, in which case it has a 60% chance to pass down its Hidden Ability. They cannot pass down a Hidden Ability when bred with any Pokémon other than Ditto. Ditto's Ability is always irrelevant to inheritance.

There's only a 60% chance to have your Sylveon pass down its hidden ability.

Source