Tahm Kench GAMEPLAY error (Devour bug)

Error occured in my last game many times - i cant devour (W) my team-mate Master yi, but i could swallow other team-mates if i wanted it. First of all i thought it is bcz of his ult, but then i tried swallow him when he wasnt ulting - i couldnt.

Please check it and try to fix.

Thank you.