Glacial Buff

So, why is it that the Glacial Buff has a 20%, 30% and 45% chance to stun, when it clearly stuns continuously after the first proc on a unit?

It seems to happen every single time, my unit get's stunned, then stunned again, then stunned again and so on until they're dead. It seems like once you proc it the first time it's nearly guaranteed to stun afterwards, if that's how it's intended to function by all means that's fine, but it's really misleading when it says 30% and procs 6 times in a row on the same unit. (also highly frustrating if your comp is centered around said unit.)