Reassign and onboarding checklist task to pending workers

Summary:

In the pre-boarding phase, when the employee is a pending worker, the HR cannot reassign tasks to him

Content (required):

In the pre-boarding phase, we setup some tasks that has to be assigned, at first, to the HR specialist that has the duty to modify them. After this update, the HR has to reassign the task to the pending worker in order that he can perform the task. I noticed that, in the reassign menu, the HR can see only employee records and not pending workers. There is not an advance search. How can the HR reassign this task to pending workers?