Operators new to a real night audit often expect it to behave like a shop till: everything settled, everything zero, then close. A hotel never looks like that. At three in the morning most of the money owed to the property belongs to people asleep in its beds.
So an open stay folio neither blocks the audit nor warns about it. It is reported as the guest ledger — a headline figure, not an exception. The one thing that does block is an unreconciled cash drawer, because a snapshot taken before every till has counted is a statement about incomplete information.
The audit closes the oldest day that has already ended, never the day in progress. It posts that night's room charges, resolves exceptions, and freezes a revenue snapshot that later reports project rather than recompute. Re-running it for the same date is safe, which matters because the usual reason to re-run is that somebody has just fixed whatever blocked the first attempt.