Kench's bug

I may be wrong, but I strongly believe there is a bug with Tahm Kench...

When I Devour minions, everything goes perfectly... apparently, the same with enemies.

BUT team mates, gosh!

I smart cast, so I thought it wasn't working because of that... then I start clicking, and it still fails :(

I realized that when I click, Kench doesn't even move towards the ally – it's like I'm not even doing anything! I have to stand by its side and click and click and click and...

I just had a horrible match because I couldn't get it to work manymanymanymanymanymany times...

Am I doing anything wrong?