Devour Stack Bug

While playing a match in ranked I was playing as Xin Zhao and just got my devour. Nothing was stacked on it yet. I went to go get a dragon to start stacking my devour. During the time of taking dragon the enemy jungler came in to try and counter it. I was about to die so Tahm Kench eat me (tahm kench is a teamamte) to keep me alive. While i was in tahm kench mouth the dragon died. Tahm kench killed it and i didnt recieve any stacks for the dragon kill.