[GAMEPLAY] Ultimate (R) activates but nothing happens except cooldown.

So basically it's as the title says. On various days since the new update, I've found that while pressing** R **to activate my Ultimate, nothing happens. It registers as having been used, as the cooldown activates, but, for example when playing Ashe, there is no arrow. This happened in my last match to not only me, but also another player playing as Heimerdinger. As you can understand, this kinda sucks. Especially when you're running away from a giant, flaming, Dragon. Just thought you should know.