Annie stun is often missing

I play Annie a lot, and I noticed that when someone dashes\flashes my ability+stun the stun won't proc at all even if they get hit.

At first I thought I just missed the abilities, but in my last match** it even procced the Luden Echo passive** when this bug occurred, and the enemy I was facing noticed it and wrote that in \all chat. Did someone else notice it?

Even if the enemy flashes right in the hitbox of the ability it seems like it just doesn't work. Facing things like Yasuo\Zed\Leblanc might be a lot harder.