[Gameplay]Attack move bug

So the way attack move should work ( or so I think ) is that you shift click and if your champion comes in range to attack an enemy and they will stop and attack. But today as a was playing Kalista ( not sure if it's for other champs haven't got the chance to test it out ), I was shift clicking behind me so if someone comes in range for me to attack them I will just jump backwards, but my champion kept running towards them trying to get in range even though I was clickink in the opposite way.