We recently fixed a somewhat tricky bug in the Patients Without Upcoming Appointments report. If you had a patient with upcoming appointments, but then deleted those appointments, the patient wouldn't show up on the report as it should. This happened because we failed to update some information about the patient in the background, after the appointment was deleted.
The bug that caused this failure has been fixed. Patients who were affected by it before still won't show up on the report, but we'll soon correct that as well. The only piece of patient information affected by this bug was the bit of internal information that determines whether they show up on the report or not. No other patient data was affected by the bug, and none will be affected by its correction.