(PoE 2) Heavy stun into break armour bug?

As the latest patch 0.1.0e just went online i realized i will stun multiple targets in 1 swing, yet only the first mob hit will actually break armour.. the others armour remain untouched?

I am guessing this is a bug as i also have a passive skill called "Shattering Blow" which states "Break 50% of Armour on Heavy Stunning an Enemy". Yet i can heavy stun 10 enemies in 1 swing and only the first mob hit breaks armour.. is that a bug or intentional?

Please let me know