Lucian's Passive Bugged?

Ill notice while in a game playing as Lucian , after i use an ability, there is a [small %] chance that his passive will not activate. I've notice this happens both on minions & champions. While it's not a HUGE issue it does sometimes disrupt game play. I.e. Using the the dash to to get the extra damage from the passive to last hit a minion. I know there is a few seconds until the passive wont fire but this will happen right after using an ability. Is there something else that could be happening or is it an actual bug??? Please look into it if possible? Please and thank you!