Lulu polymorph Vlad (w) pool bug

Got into a fight in lane vs. a Vladimir as Lulu. I cast my w, whimsy to polymorph vlad. The cast goes off as you can see in the clip by the cooldown on my spell bar. Vlad absorbs the total 1.25 second duration while in his pool and comes out of it acting normal. My character did not move faster or show the animation effect of casting whimsy on herself so I did not misclick the cast. Vlad's W does not cancel CC, it only makes him untargettable. Yet my target spell hit him and did nothing. Fix the interaction between the spells please, Lulu's polymorph is a huge tool in her kit considering it has an 18 second base cooldown and if it doesn't work like in my experience, that creates a huge problem.

EDIT: This is my first time posting a bug in awhile and actually first time posting a twitch highlight to show proof so I don't know if the link is working. It does go straight to the highlight on twitch, but to me on the support page its just showing my livestream. Ignore that if you see the same thing and just go to the twitch vod.