I apologize for any confusion regarding your survey results. I believe what is happening is you are viewing both the Completed and Partial results for the survey. The question is required and they cannot complete the survey without answering it. But if they get to that question and then navigate away from the survey, our system will still track what they did answer.
What to look for when you're on the survey results page:
You can change the view to only show "completed" respondents. If you change the view to "partial" you will see that it corresponds with the number of respondents that did not fill out the personal information section.