Tahm Kench Can't Eat Allies

I'm not entirely sure what recreates it, and it may actually be the cooldown bug and not Tahm himself, but it happens a lot when I'm playing him. I go to eat an ally, I know that the ability is up according to the HUD, and I walk next to them like I'm going to, and then stop. To be more specific, I walk to their location when I clicked them, and if they continue moving, I won't follow. Even when right next to them, spam clicking just walks me in circles for a few seconds.