As a HR Specialist I cannot add any internal candidates to a succession plan - why is this?

Summary:

As a HR Specialist I cannot add any internal candidates (employees) to a succession plan when I create a succession plan - why is this? When I search for the internal candidates (employees) in the Name field nothing comes up?

I can view employees under my AoR under Person Management

Content (required):

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

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