Xerath 'Ghost Cast Arcanopulse' bug

Not sure what else to call it so Imma call it "ghost casting". Should be quite a rare bug because it only happened once ever. I wanted to insta-cast Arcanopulse and follow up with a Shock Orb stun however the Arcanopulse didn't go off instantly and remained charging, during this time there was no Arcanopulse channel progress bar and the Arcanopulse didn't actually fire at all, and I was locked in charging the Arcanopulse, meaning I was unable to fire off a stun that would've killed my opponent faster. It wasn't forever though, around the same time as it'd take to fully charge Arcanopulse and have it time out was around the time it took to go on cooldown so I was able to cast everything normally after just a few seconds. Luckily this happened in a 3v1 scenario so we easily overpowered the one guy with numbers anyway.