The Students - Returning vs New report looks at the parents' country field instead of the student's country. If a student is missing from the report when using the country filter, the field on their Contact Card may be blank. Please check the student's parent's profile through:
  1. Core > People Finder
  2. Locate the User and open their Profile and Contact Card tab
  3. Under Address, Click the pencil next to their Home Address
If the country field is blank, select the correct Country from the drop down then click Save & Exit.