Skills going on cooldown but not activating?

biurb

Hey, a small problem with my "impossible to catch" skill - it may extend to other skills but it's most obvious with impossible to catch as it's a self cast. 1 in every 10 or so uses my impossible to catch will be put on cd but not activate - my character's skin does not change and the buff does not appear on my buff bar. It happens in situations where I'm not even being attacked much less cc'd, it'll just randomly decide to not go off but gets stuck on cd for 18 seconds... what's up with that?