Kassadin's skills sometimes don't work

I have no idea if this is just me, but whenever I play Kassadin, my skills sometimes don't work at first; I have to hit the skill key twice in order to activate a skill. Extremely annoying when I get "juked" just because my Rift Walk failed to work... Yes, my keyboard's plugged in properly. Yes, I repaired and reinstalled the game. No, this does not happen with other champions (that I've played as of yet). This has been apparent as of the 4.19 patch, and it doesn't seem to be fixed in 4.20. Kass is one of my favorite champs, and I'm just outraged to be crippled by unreliable controls/abilities. If it's just me, feel free to smash this singular bug. If this is a bug that others are experiencing, time to play the dreaded "wait and see" game...