Tristana: Rocket jump is ignoring cc

i played a game vs a corki as blitz and everything was fine. when i pulled him he would be pulled, even during valkarie which would be interupted and he would be pulled to me. when i used my knock-up it would cancel his Valkyrie at the point it hit him. basically everything was working fine

next game i was vs a tristana.

and EVERY time pull her and used my knockup she would rocket jump away mid knouckup like it never even hit her. i would pull her and she would rocket just mid way out of my pull

it was freaking impossible to kill her because her rocket jump would completely ignore my cc.

yet skills like reksai's knockup is able to interupt her rocket jump mid jump. which is again normal

so idk what the issue is... i dont see why tristana escape and enage would fuction any differently vs a reksai knockup or a blitz knockup. or why trisana can rocket jump out of my blitz pull but corki cant Valkyrie out of it