If a student is not showing on a report as expected it may be that they have a hidden status on the system. To check this please go to Admin > Students > Group Updater - changing the student attribute to hidden pupil. If any students say true this will mean they will be hidden from reports and the census. You can amend this data in this area.
If you have checked this, check whether you are reporting on data for last year.
Data on ScholarPack is stored against the student, reflecting their current year and form, rather than the one they were in at the time.
In order to see data entered against a set of students from a previous year, make sure to select the year and/or form group they are in now - for example if a student was in year 6 last year when the data was entered, you would need to select year 7 in the selection as that is their current year group.