Evelynn Ravage Proc Sound but not Ability?

When I use Ravage the sound will proc but the ability will not be used. This happens when someone flashes out of it. Or if they go into a bush and disappear. Or if they grab thresh lantern, or last second teleport. It happens every time. AS if the ability never was used. Yet the sound for the ability goes off saying that it was used. The ability then remains still usable even after the sound went off. Why is this, how can I fix it, I miss out on a couple kills a game just because of this. Eve as is can be challenging to get those last minute kills and if you cant even have an ability assassinate a guy last minute then another reason why she isn't a true assassin.