Rek'sai interactions

So as I am playing Rek'sai with the new changes I was wondering if her ultimate (I'm just going to say R from now on) was supposed to be a point and click target ability like Lucian Q, Nocturne R, Vi R, Ekko E, Fizz Q or Pantheon W or more of a skill shot like Warwick R? I was playing a game where I use my R and clicked on a target but the target did not take damage from my ultimate simply because he dashed away. Is Rek'sai's ult meant to be like Lucian Q where as long as you move out of range of it in the last second you dodge the ability? This makes sense and adds counter play to the ability but seems a little silly that if the target is clearly within the R range and if you were to ult a target that is hypothetically 100 units away but dashes 500 units away during the cast time but still within the R range they go unscathed.

TL;DR Rek'sai ult used, target dashes away and receives no damage, counterplay or bug?