[Gameplay] Tahm's devour isn't working properly with Target Champions Only

Because sometimes I was eating minions instead of champs with Tahm, I wanted to try out the Target Champion Only hotkey. I created a custom game and tried to use my devour on enemy minion while pressing target champion only hotkey, but it didn't worked out and devoured the minion whereas it should have ignored it completely. I tried to auto attack the minion while pressing the target only champ. hotkey and it ignored them, so the hotkey is working. I also tried to use target only champ with Malz.'s E, and it worked. So I thought it could be a bug with Tahm's devour.

I tried it with both classic and master chef skin, and it didn't work in both times. I only tried it on custom game. Hope I explained it well.