Unable to create grade in Workforce Structure

Could anyone check why it is not available to create a new grade in 'Workforce Structure - Manage Grades'?

The user have HR role including Privilege: Manage Assignment Grade Rate, and Admin role, and when I access to Mange grades, there is no button to create new grades.

We also run the below processes

- Retrieve Latest LDAP Changes

- Send Pending LDAP Requests

- Send Personal Data for Multiple Users to LDAP

- Import User and Role Application Security Data

Please refer to the attached file(Diagnostic Log: Check Function Security Diagnostic)

Thank you