Don't know if you ever figured this out but we had the same problem. There are two places to check to fix this. The first is on the survey itself, verify the "Anonymize Responses" is not checked.
The second is an option lower down the record under "Related Links" (Geneva) that says Remove or Enable Public Access. Any Public Access survey page will automatically make all responses come in as Guest as no authentication is required to take the survey. Hope this helps!
