Confused Darius is Confused [Gameplay]

Seen this happen at least 3 times today. Sometimes when a Darius would ult, the full animation would play out (there would be no inturuptions such as croud control or anything that would cancel the ult), said Darius' ult would go on cooldown, meanwhile, the one who was ulted would take no damage (except from any stacks of hemorrhoids... aah i mean hemorrhage that was on said ult target) Don't know if this is a bug or... yeah

The three times it happened to me today

1. I played Darius, had 3 or 4 stacks of hemorrhage on enemy, ults them, they do not die, they don't even take damage. They are confused as I am (SR)
2. Darius on my team had an ult that was supposed to do a kill, nothing happened. (ARAM)
3. Was a Shen, had ~250 health left, dived in because snowballs are fun as fk with Shen, gets ulted by Darius, with ~2-3 stacks of hemorrhage... walks out alive.... I was as confused as he was. (ARAM)

(has no photo evidences yet, will try to record a reproduction)