Missing EEO Data

Summary

Why are candidates missing EEO data when it is mandatory?

Content

Hello,

We are ramping up for AAP reporting at our organization, and when I pull an OBIEE report with candidate EEO data, about 1% of our candidates have blank Gender, Race and Ethnicity fields.  A blank value differs from "Undisclosed" which is one of the options.  How are candidates bypassing these forms when they are mandatory?

I thought that they were agency referrals at first perhaps, but for many, that's not the case.  It appears they've just applied as normal through a job board.  

A screenshot of the Diversity section on their profile shows the same.  Any ideas?