Kalista able to auto-attack while stunned

Played as Twisted fate against a team with Kalista. When I stunned Kalista with my gold card she auto attacked me through the whole stun duration (she didn't jump around though).

How to recreate: Play Twisted fate against Kalista Stun her with a gold card stand in aa range and let her aa you Kalista should stay frozen in place but be able to aa you