Custom HR role is not able to see all the candidates while adding to a succession plan

Summary:

Custom HR admin role is not able to see all employees while creating a succession plan.

Navigation - My client Groups - succession plans - create succession plan - Candidates drop down is showing only few employees.

He should be able to all employees in candidates drop down. How to achieve this?

Content (please ensure you mask any confidential information):

25 C, Redwood

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):