Not able to see user in approvers listing in Project Administration

Summary:

Dear all experts, I am not able to add user in approvers.

In the past, i was able to see each team member usernames and add them under approver.

Recently, its loading my username only and it does not display any other username.

Content (required):

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

23.10.0

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