Unable to load BPM Tasks for users

Summary:

BPM Tasks were not loading for Application Users

Content (please ensure you mask any confidential information):

Hello Experts,

We are configured BPM Approval flows for CRM Users in B2B Service Module for Service Requests.
Users were unable to view the BPM Tasks in Emails and in worklist application.

The page is blank when task was viewed.

Need to know which privileges or the roles required at minimum.

We have

Service End Users: Roles (Customer Service Representative and Employee)
Service Managers: Roles (Customer Service Representative, Customer Service Manager and Employee)

With this roles users were unable to view the BPM Tasks