[GAMEPLAY] bard ult interaction with kalista ult

I am not certain if this is a bug or not but i feel i should say it anyway. In my game i was playing bard against a Kalista blitz lane. When my team was chasing down the enemy team after a successful dragon fight i ulted blitz. Kalista was then still able to use her ultimate to pull blitz free even though he was still in stasis saving his life.