GAME BREAKING BUG UNTARGETABLE ABILITIES DONT WORK SOMETIMES

Almost if not all the abilities when you go untargetable do not make you untargetable sometimes I have been killed as yi and fizz when I go alpha strike or on my troll pole I have only noticed it one time as fizz but i thought it would be only a one time thing I have been hit with aoe spells like sona's ult as yi even when im mid alpha strike. i cant record gameplay (rip league raplay system) here a vid from a youtuber snowbird he dies from a tristana autoattack while using e at 3:10 https://www.youtube.com/watch?v=GsNmOyB0Lnw

Edit 1: report an actual bug get downvoted lmao