ZAC Jump cooldown not resetting if not used

I've had at least 3 games where i charge up the jump on zac to go in, and wait for the perfect moment, and it never comes, so i cancel it at the last second, and the zac e cool down is supposed to half, however it has recently been either doubling the cool down from just over 10 seconds to 20 seconds or keeping the normal cool down without halfing the cool down for the canceled jump...

being a frequent jumper and ganker with the e this is a huge problem if i can't jump when i need to during a team fight or get killed and cant use my e cuz it's still on a 20 second cool down... i would appreciate it if your insect squashing dept. could look into this. thanks