Sejuani ult may be bugged?

I don't have a link since my recording didn't go through, but I noticed something weird with Sejuani's ult. I included a link to the match history where the question lies.

Basically, my ult was going off and connecting to the enemies but I noticed they NEVER stunned, only slowed. I thought at first maybe I was just hitting the minions but I know I ulted a few times out of lane, for example: tribush on bot lane. I would see the animation go off on them and know it connected but the ult itself was never stunning at all.