Azir ultimate still has Bugs?

Near the end of my last game, Azir used his ultimate while fighting Diana

His phalanx passed straight through her, not damaging or pushing her away

all 5 of us saw it happen

at that moment, Diana had her Pale Cascade active, and was also Exhausted by Azir (coincidentally, it also passed through the remains of the outer middle turret, as I know that his Ult has had bad interactions with turrets before)

I don't have the means to try and re-create the event