[BUG][GAMEPLAY][ABILITY]Dredge Line vs Spell Shield Interaction

I was playing a Sivir tonight in ARAM and there was a Nautilus on the other team. Every time he threw this anchor at me (used the ability "Dredge Line"), I countered it with my Spell Shield ability. He then fast-moved half the distance from him to me. I wasn't affected, but he did get movement out of it. It is my impression that all effects of the "shielded" spell should be negated, not just the ones that affect me. Plus, it also looks really unpolished.