Tahm Kench unable to eat teammates

My last ranked game i played tahm kench with a jhin adc, everything seemed fine, i was able to eat him and all that, but after a while i wasn't, i don't know what occurred to make this happen but i could eat everyone else on my team but him. I don't know if this is a specifically new bug with jhin or an older one that can occur with other champs, and i don't know exactly how to recreate it, this has happened a few times with other champs to me, but has usually been on a game by game basis