[GAMEPLAY] Syndra Double Ult Bug

I just had a game with an enemy Syndra ulting my fellow team member Ekko right before he used his ultimate to wrap back in time. When Ekko finished his ultimate Syndra's Ult still followed on and he took damage, then she immediately flashed and somehow ulted me and it threw balls and me and Ekko! It's an old bug that hasn't been fixed please help! :(

Edit: It's casued when an enemy goes untargetable after she cast her Ult, it doesn't go off cd, and allows her to recast again, strangely allowing her to target multiple foes. :(