You have a form: Online Admission, Online Reenrollment or Common, setup in NetCommunity. At first, you have a field which is visible on the form and users submitted data to this field. It is visible when clicking the user's name under form data.
After hiding a field and viewing the form data for the same user, you now notice the field is also hidden here.
When viewing the form data by clicking on the user's name, the fields which are displayed are dynamic. If you hide a field on the form, it will also hide it from the form data view.
If you chose to include the field in export, you can export the user's data to see the already submitted information.