[GAMEPLAY] Caitlyn - Ace In the Hole Bug, becomes untargetable when fires rifle

I went to go snare (as morgana) Caitlyn as she was channeling her ult Ace In the Hole, except my binding went right through her and didn't snare her. I don't know if this is an intended interaction because the binding connected with her just as she shot her rifle. Not sure if she is supposed to become untargetable. Please correct me if I'm wrong! There is a link for the video above.