Dark Flight

I was playing League on Summoner's Rift against Nautilus, and another game against an Ahri with a similar problem, and he made a grab with dredge line that didn't seem like it should have hit. I know in his Dark Flight ability it says that "movement effects will take effect after Dark Flight, but when I was using it over a wall his Dredge Line "hit" me after I was over the wall but before I landed. The similar problem I mentioned with Ahri was she interrupted the ability with her charm (pulling me from the air back to the ground). Is this a bug with the ability, or intentional? Why then would they interrupt it instead of after I land? (Will try and get video if needed)