Thank you for contacting Syncfusion support.
As you mentioned, you need to set Schedule AllowAppointmentDrag as true to enable the appointment dragging in Schedule. AppointmentDragStarting event will trigger start dragging, AppointmentDragOver will always trigger at the dragging and AppointmentDrop event will trigger after dropping the appointment in the Schedule.
You can also refer our user guide documentation regarding the same,
We hope this helps.
Subburaj Pandian V