Scheduled Reminder fails on event participant status criteria

Set up a scheduled reminder designed to target contacts that have registered for a given event and have a participation status of 'Pending from pay later'. Ensure that 'Record activity for automated email' is checked.
Double check that there are in fact contacts in the database who meet the criteria.
Manually add an additional contact who will receive the reminder.
Trigger the 'Send Scheduled Reminders' scheduled job or allow it to run based on cron.
Search for 'Reminder sent' activity records.
In my test I found just one activity record, which was for the manually added contact.
No information was present either in the CiviCRM log or the PHP error log.
This suggests that the reminder is unable to identify those contacts that meet the criteria for the reminder, and is only sending the email to the manually added contact.