Manager not able to see his employees' Performance Documents from the tab Performance

Summary:

With the custom Manager, we are not able to see documents from Performance tab on employee's profile

Content (please ensure you mask any confidential information):

We are currently using custom roles, and the custom Manager is able to see the documents from Goals and Performance Overview page but is not able to see Performance documents from his direct reports profile when the documents are assigned to another manager.

We tried adding the Performance Management Line Manager role to the custom Manager and it worked, but this role inherits a lot of roles and privileges that we cannot assign to the custom Manager.