Yep, had it happen to me a couple minutes ago. It's knockback locking more precisely, but amounts to the same thing. This was supposed to be fixed ( in the crudest way possible ) by adding CC immunity.
Obviously it doesn't work reliably. Since I noticed this only once since 1.6, I can not give detailed insights about the conditions it may or may not require. It was definitely Puncturing Sweeps causing it though, as the player did not use any other ability on me.