Lux Ultimate Bug

When Lux casts her ultimate, its a second cast that can't get interrupted, her ult either goes off or it doesn't when killed, but right now, but recently for the past 4 patches Lux's ult goes on CD when killed during cast, but it doesnt go off, her ult is supposed to refresh but instead it goes to CD when killed and the icon shows you have it but it doesnt let you use it. [sg-lux-2]