How to get LOV of agents in "Assigned To" field when creating a Case under HR Help Desk?

Summary: How to get LOV of agents in "Assigned To" field when creating a case in Help Desk?

Content (please ensure you mask any confidential information): I have assigned the user following roles:

Next Gen HR Help Desk User

Case Manager

Case Worker

Human Resource Specialist- "View all People" security in "Public Person" and "Person"

Employee- "View all Workers" security in "Public Person" and "Person"

When I create a Case through Help Desk > Cases > Create Case, I am not able to see any agent name in the "Assigned To" field on the page, also I don't want to give the Next Gen HR Help Desk Administrator access to the user.