Kalista BUGSPLAT BUG!

Me and my friend and I decided to play some PBE today (7/7) and played a Kalista & Tahm bot lane. It seemed to be a really easily repeatable bug, all i would do is ult and Tahm Kench would bugsplat every time, and sometimes it seemed to affect others (they would also sometimes bugsplat.) This is easily recreatable, Please investigate! (All kalista has to do is ult tahm kench, as in he is on your team and you pick him up and make him invincible, then he bugsplats)