Bug with Annie stun and wind wall

What do you mean by that?

1. What do you mean about Annie's stun?

2. What about Yasuo?

I'm going to guess that you mean that if Annie uses her Q while her stun is up and Yasuo blocks the projectile with his Windwall, Annie's stun is not consumed. This is not a bug, it's intended.

Annie's Q does not consume her stun unless it actually reaches her target. If for any reason the projectile disappears, such as being blocked by Windwall or the target becomes untargetable, it is intended that Annie's Q does not consume her stun.

Elaborate please.