Why can't I add a person as an interviewer (not available to select in LOV)?

Summary:

I'm unable to add the Hiring Manager for a job requisition as an interviewer. When I type in their name they don't come up.

Content (please ensure you mask any confidential information):

I'm unable to add the Hiring Manager for a job requisition as an interviewer. When I type in their name they don't come up. Anyone know why this would be?

The person is an active employee and was able to be added as the hiring manager.

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

25B

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