How can I update the Candidate Type for a current employee?

Summary: We have a current internal employee that is not able to apply to internal postings despite being a current employee. His Candidate type is showing as External and I need to update that to show as Employee but am unable to find where to update that.

Content (please ensure you mask any confidential information):

This is how the candidate (employee should look)

How the candidate looks

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

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