(Gameplay) Fizz E interaction with Blitz's E

Fizz is not immune to knock up (and damage) from Blitzcrank's E (Power fist) during Fizz's Playful/ Trickster untargetable window. Found out about it numerous times when I was playing Blitzcrank and that I was able to knock Fizz up and stop his Playful/Trickster mid-hop despite Fizz being partially immune for a few times. Please could someone look at it and see if it is intentional? Thanks!