When previewing the Custom Certificate with Trainee info, the search box will only display users who have been enrolled in the Course. The preview will display, by default, Trainee names in alphabetical order. Select a Trainee name and then click Download PDF Preview.
If there are no Trainees enrolled in the Course, then the search box will display "No matches found" but a preview can still be obtained. Instead, click the Download PDF Preview button and the certificate information will display the Trainer/Administrator that is currently logged in.