Nani Ult Bug [GAMEPLAY]

In my most recent game there was two times that the ult was sent backwards when I had mi curser on top of the enemy team. It wasn't caused by the minimap my curser would be directly over a champion and it would end up going backwards and ruining the engage or fight. I have no screenshots or video because I don't record and it's seems random so I don't know how to recreate it.