Malzahar's ult bug?

Recently i played a normal game, i was mid against a gold IV syndra, no big deal. But at one point in the game I ulted syndra with my malzahar however, she just walked out fo range like nothing was happening, though my ult got on cooldown. Maybe it was a morgana shield, but i dont think it can cancel surpression. And I also looked into her item build and didn't see a quicksilver sash too.

Is this a bug of some sort?