Candidate search returns only unapplied candidates

Summary:

We're creating candidates and candidate job applications with Rest API and HDL. Source=Import and Source Medium=HR for those Candidate records. The Candidate Search page returns only the candidates who have not applied to a job. Once we enter a job application and thus link the candidate to a requisition, Candidate Search page does not return that candidates anymore, we then can access those candidates only via the Job Requisitions page > Job Application

Is it a normal behavior or are we missing a specific configuration for Candidate Search page? Candidate Search page needs to populate all candidates either they are applied to a job or not.