So I tried to start building a new airport, doing the layout and all the before getting construction underway but as I was laying out my Bathrooms I lost all my money. It changes to $NAN.
I have worked out that it is caused by the Bathroom and Staff Zoning (Not Staff room), when you designate the space it takes away whatever money you have.
It happens both when game paused and when live, I have checked and it does it when the building is complete as well making it unplayable in my opinion.
I am running Alpha 29.5-1