Service reminders can be viewed in 2 main ways:
Through the service reminder report.
Using the 'View all service reminders' on the customer tab.
The Service reminder report within the reporting section shows you all instances of that service reminder, whether the service reminder job has been added or not. This should be used for historical/analytical purposes.
The 'View all service reminders' list will show you any service reminders that have not had a job booked. This is where you go if you want to chase up customers or send the reminders out.
You can see the report above (picture 1) shows 2 service reminders. The top one has been sent and booked into the diary. This will not show on the 'View all service reminders' list (picture 2) because it has been booked in. This is the 'View all service reminders' list for the same account on the same day.