Neeko's Ultimate is Immune to Suppress????????

I honestly don't know if this is a bug or if this game is just this unbalanced, but this is ridiculous. I was playing a game as Malzahar against a Neeko, and every time I'd see her use ultimate I would respond with my ultimate. But instead of canceling the channel and suppressing her as it should, she would finish the ability and escape from my ultimate without any evidence of every being cc'ed. In fact I would be stuck because I was stunned whereas she was no longer suppressed. Why doesn't Malzahar's suppress stop Neeko from channeling the ultimate? Also what should I do to outplay her if my ultimate is completely useless???