[BUG] Syndra E failing to stun

Ever since the range buff to Syndra's E, there have been issues with it not behaving properly.

If I use E(Scatter the Weak) on a ball I just threw with W(Force of Will), it will slow the target instead of stunning them. It does not happen every time, but enough for it to be noticeable (50/50). The target will be outside of range for the W to slow them.

UPDATE

From what I can tell by the visual effects casting E while her W is in the air "knocks" the W farther than it's intended range (the W landing animation happens after the ball gets pushed). Is this intended behavior or should the E be stunning instead?