You see a low health target as Garen, and you press R. You hear the animation sound, but you don't see the animation. That is because someone else got the kill even though you ultimate was not used. If the target dies, your ultimate goes on cool down. Many times, I don't even get an assist. It just goes on cool down.
I use BaronReplay and found that the times I thought I was popping my ult and it was killing them, I was actually hitting my ult as another team mate killed them - the result is my ult hits a dead body so it goes on CD - don't get the assist because the damage didn't apply. It's a rare ability use issue - what I've found is that it's the "casting time" of the ultimate so if Cait's ult hits a moment before the ult, the ult will "hit" but do no damage as the target is dead. No assist... but goes on cooldown. Not sure if this occurs enough to warrant a bug fix, but it is absolutely annoying.
