[GAMEPLAY] Annie's passive doesn't work in special cases

This is a bug that's been around for years, but recently its become more common and its incredibly frustrating when it happens. I don't think I've been able to figure out a way to have it happen 100% of the time, but basically if you full combo someone (R/Q/W) while the stun is up, the stacks will be consumed, the opponent will take the right amount of damage, but they just won't be stunned. This doesn't happen as often with just the Q/W combo, but it can.

I know that I'm actually hitting the enemy with all my skills because they're taking the right amount of damage and my skills are going on cooldown; they're just not getting stunned properly.

At the end of this combo, I usually end up with 1 stack of the passive, even though I should have 2 stacks (having went in with a fully stacked passive and used three skills).