Zoe Ult - Leblanc Chains interaction

I was playing as Zoe against a LeBlanc just now, and while LeBlanc had chains on me, I ulted outside of her range, then the chains popped. I was still snared as if I never moved. Is this the intended interaction?

Also Just to clarify, I activated my ult and (as far as im aware) when I was fully extended the chains sound activated as if I never moved. I was NOT mid Ult cast. Another wierd thing, the chains disappeared, but still rooted me.

Any thoughts?