Velkoz ultimate is bugged

So i put this in the german forum but no one answered so i try it here. You know how replay.gg works? if not the site explains it itself in the link i send you i played Velkoz and 2 times this game my ultimate did no damage it did the initial damage and nothing else. once at around 18 minute but the better example is at 23:05 you see me ult 4 people they all took the initial damage but no other damage i casted for 3 seconds i lost a ranked because of this so yeah pls fix thanks