Orianna and Ultimate Hat

I encountered it now a few times, going to add a few vids soon. The problem is that while playing Orianna, i dont get the stacks for Ultimate Hat for each time of use. Normally you should have max stacks on Ultimate Hat after using the ult 5 times, regardless the champ. But not when (i am) playing Orianna. Sometimes it works, sometime i have to use the ult a few times ( 4 is the current highscore) to get the additional 2% CDR. I am only using the Winterwonder Skin, didnt try it on classic skin yet. It also happens on all maps (SR/HA/TTL) and also regardless of ranked or not ranked