Day off: travel day or at home. On the road, a day off is a travel day: band and crew are paid the travel rate and get per diem. A day off at home is unpaid and earns no per diem.
ATOM decides on its own for each day marked Off: work booked that day, a hotel that night, being away from home, or the day sitting between work days all read as on the road. Open the day (Overview) to see what ATOM decided and why.
To change it, tap Make it a travel day (paid) or Day off at home (unpaid) on that day. Let ATOM decide puts it back. Crew Pay, the Pay Ledger, Budget, Money Home's Days on the road and the Tour header all follow the same answer.