[GAMEPLAY] When Lulu Casts E and Target Flashes or Jumps Wall, Pix Cannot Follow

I noticed when I was playing Lulu that when I cast my E on an enemy who flashed a wall that Pix did not make the jump, but instead "walked" around the entire wall. By this time, the ability was no longer on the target and it cost us a kill. Later at the dragon pit when I cast E on my ally Jax, he hopped the wall and again, Pix flew around the entire wall and THEN I was able to get a Q off. This doesn't seem right to me. Nowhere in the description could I find anything about displacement issues. From my understanding, if E is cast, it should not then have to re-follow the target. If Jax can jump a wall, Pix can fly over it.