Blackbaud NetCommunity users are not able to search fields in the directory search when marked as private in user profile. For example, John marked the email address field in his Profile Form as private. When searching the directory for John's email, firstname.lastname@example.org, no results are returned. You can find John based on other values that public, for example First Name John.
Fields that are marked as private in the user profile will not be searched on or return results in the directory search. In order to search on that value, the user will need to update their field privacy to be public, if desired.