Kayn's ulti

Every time kay's Ulti gets cancelled for some reason, its shows that you still have your ulti on to use it again, but u dont really have it, when you try to use it, it is on cooldown and u need to ctrl click so see the cooldown, i have died sometimes because of this, i think i have the ulti on and i m all in them but when i spam the ulti i realize i dont really have it because it is on cooldown but it doesnt show in game, ty.