Khalistan bugg

Hello, recently I have been playing a lot of Kalista and whenever I ult my teammate that is soul bounded to me comes to me and when he or she leaves to get the Knockup, he or she instantly comes back me to me. I don't know if this is a bugg or it's just how kalista's ult works but it seems like a bugg. Has this ever happened to anyone else ? Sorry about the title fucking auto correct.