Empty values in the Export files are due to not fully answered Questions. For example when an open text Question is answered with no text.
It is possible to avoid empty values by making the Question mandatory. To do so open the Question in the Survey and select Yes inside the Required dropdown menu:
Now the customer has to fill in something or make a selection.
Not in every case you want to have a Question mandatory. If you want an export only with completed answers you can configure an Exporter to have only these lines exported which are completely filled out:
Having no checkboxes set will give you all record sets, including with status not started.
The check box Only with responses will eliminate the record sets where the customer didn't even start the survey.
The checkbox Show and count only valid responses will eliminate record sets from customers who are not fully completed or don't match customized rules if exist.