[Gameplay] Tahm Kench can't eat teammate shaco in ARAM

I was just playing an ARAM game as Tahm Kench and could not save our shaco at all, at first I thought it was because I was to late. But later i found out I could not activate devour on shaco at all. I kept spamming it on him but tahm just stands there. I have no idea how to reproduce it or wether it happens often or not. I did just install the beta client so maybe that has something to do with it. I will try and reproduce it in a custom game when I have time.