Illaoi E, Test of Spirit "ability" interaction [GAMEPLAY]

Hi! I am an Illaoi main, and I've constantly encountered the error that Illaoi's E, test of spirit does not proc manaflow band, or phase rush counts. Upon hitting test of spirit on a champion it does not yield a count towards phase rush or 25 mana towards manaflow band. Is this meant to be coded this way? Or is this a bug? While it's not a huge problem, it seems to be a bit restraining to my keystone options, and the amount of time it would take to stack manaflow band, thanks!