Sitecore 8.2 WFFM some data not appearing in form reports

A strange issue came up whereby the data inside the form report for a WFFM form in Sitecore 8.2 was not all appearing. In this case the form consisted of three fields: Email address, first name and last name. There was a long history of all of the data appearing in the form report, then suddenly email address stopped recording.

Data disappearing from WFFM form reports

After some investigation it turned out that the Save checkbox on the Email address field (under the form node) had somehow been unchecked. Re-checking this field, publishing the form and submitting test data confirmed it to fix the issue of some data being missing in form reports.

Save option on a WFFM form field