Sanctum affliction "Floor Tax" removing coins AFTER selecting the first room of the new floor

I have had the Floor Tax affliction and on getting to the next floor I saw that I had around 400 coins which lead me to select a benelovent fountain room only to discover the coins get removed after the going into the first floor instead of looking at the map of the new floor.

Not the biggest deal, still sounds like a bug, because the affliction states "Lose all Aureus on floor completion" and not on beginning a new floor.