Sivir Spell Shield

Did they tweak it recently? I've been noticing it just flat out not working occasionally.

I've had several recent ocassions where I was hit with something like an Annie Q stun or a Kayle Q (the one that slows you down) and I still was killed even though Sivir proc'd the "Nice try!" voice over. I seem to still take the damage, just the effect (the stun, the slow, etc) is negated.

Is this suppose to be working this way?