Manager Name field not available in Onboard Configurable PDF form

Summary

Not able to choose the field Manager Name for a PDF form in Onboarding. Has anyone else experienced this.

Content

I am able to use the Employee Manager Field when setting up Email Notifications (See screen grab in attached doc) in the Onboarding Administration area. So I know the field exists in the Employee Fields list.

I'd like the manager's name to appear on a dual signature Configurable PDF form that we use for onboarding.  But that field or something similar to show the employee's manager is not available when I choose the Employee Merge fields (see comparison screen grab in attachement) when editing a configurable PDF.