Unable to create a Performance Document because the Performance Document Manager field is blank

Hello team,

While creating a performance document for the employee Performance Document Manager defaults to their line manager. Here in this case the employee reporting to a non worker, the Performance Document Manager is blank. However, i could see the manager in previous step.

We ran the Manager Hierarchy process as well as assigned the duty role of Performance Management Line Manager but no improvement yet.

Attaching the screenshots as well.

Regards,
Harish P