When we filter a list of students and export to a spreadsheet, one of the fields we want to pull is the students' personal email address. The issue is that some of the students' email addresses pull into the report and some do not... even if the email address is entered for the student. When we were looking into why this might happen, we found that on the report the field is "Personal Email", but on the student info tab the field is "Home Email"... does that make a difference? Is the "personal" email address from somewhere else in Populi? Where does the report pull the "personal" email address from?
Whenever you're including email addresses in an export, the only way to guarantee an email address will show up for everyone is to select Primary Email. The other fields you mention are Custom Info fields that your school has created. Unfortunately, these fields duplicate information that Populi already tracks—to wit, Email Addresses (whether Home, Work, etc.).
In addition to using Primary Email, I would strongly recommend transferring whatever email addresses you've collected using those custom info fields to Populi's built-in email fields—those email addresses will be a lot more useful to you after you do so...