Expired Appointments are still there

All the expired appointments are automatically considered as REMOVED, but they will stay in PENDING status until someone will try to search for an appointment with the same employee or will try to access to the order summary page.

The Keep Appointments Locked setting defines the number of minutes for which the system should keep the employee of a pending reservation, as "locked" so that nobody can choose an employee that is being reserved by another client. When a customer searches for an appointment, the system will remove all the expired reservations with PENDING status. You should set an high value to ignore this parameter (e.g. 99999999), otherwise all the customers will be able to confirm an appointment only within X minutes.