Why don't all workers have person profile?

Summary

Why don't all workers have a profile code associated, even if the person profile is autocreated?

Content

Hi,

when configuring the person profile, the flag "Autocreate Person Profile" was activated. But, when I go to Report and Analytics area in order to have the list of the profile codes, not all the workers have a profile code associated: why? The workers that have the profile code column NOT blank are those that have the role necessary to access to Me > Career and Performance > Skill and Qulification page and so have already filled in their profile: can this be the reason?