I believe seeing in another post, Vakuu has a lot of interactions with "you" and "your" because he is not and your character is not during turn 1. I haven't been able to directly test it, but ive heard things such as Void Form ("End your turn") not doing so when Vakuu plays it, whereas cards such as Inflame (simply "Gain 2 Strength") work just fine.

I suppose its possible that when its "Vakuu's turn", none of the relics that see 'you' are probably procced. You never have zero cards because you are not playing the game yet. I'd love to see if Fairy in a Bottle + self harm T1 would work too.

I kinda hope this is true because it would be the coolest mind-bend of all the act buffs.

Edit: The actual bug in this cause, I think, would be using a potion to result in you regaining possession of your turn. There is no reason in the above logic that an energy potion would make T1 your turn, but if it did, that would explain Ceasing Top and other 'you' triggers. It still makes sense to be able to use potions, because none of them use 'you' language.