Tahm Kench bug

I've played Kench a few times now and I noticed that anytime i have 3 stacks on WW and he's ulting someone, my devour doesn't do anything, it goes on CD, but ww remains ulting the person, and does not make the person (being ulted by WW) movable again. I have tried consume in other scenarios, like for vi's ult and Caits, and he stops their ult when he does it, but with ww's not only does he not stop it, it puts it on CD.

Another one I noticed was when gnar (little gnar) goes big gnar inside you, he pops out, or when he goes from big to little, he pops out again.