Cho Silence Hitting Vlad in Pool

Alright, had an argument in a game whether this is a bug or not -- looking for clarification.

I was playing Vlad, and Cho's silence was silencing AND damaging me in pool.

I was very much in pool, it wasn't even close where there could be any speculation like, "maybe it hit at the same time you cast."

A team mate argued that it's working as intended, as Vlad is untargetable but not immune to AoE spells. I know this is 100% false as I've sat in AoE's before while in pool and taken zero damage.

I'm aware that tethers such as Fiddles drain and Nocturne's fear will remain on Vlad, and that makes sense... but I don't understand why Cho's silence would be an exception?

Are there other exceptions like this, or is this just a bug between the two abilities?

Maybe someone from the live balance team can give a definitive answer, as it doesn't seem clear to me? :) @Meddler