Erica is right for the known visitors. Once the visitors are known with all information gathered by fields in progressive profiling, the fields set in progressive profiling stop showing up. Can you clarify if you need the same fields or do new fields come up(which you want to consider outside of progressive profiling) once the visitor is known?
If the number of fields is the only issue, you can bring it down to 4 by including 3 fields by default and setting all of the rest in progressive profiling box. To make sure that only 4 fields appear, set number of blank fields for progressive profiling as 1. Is this the issue you are facing or is it something else? Please let me know.
Hope this helps!