You may have typed the name and not selected both the username and person’s name. This makes it appear that you have added the person but have only added text to the user list rather.
When you are adding a new user on the User Rights page, you must select the person’s username when it populates as you type it into the +Add with custom rights or Assign to role text boxes. In the example below, the user must click on the site_admin (REDCap Admin) auto fill or type out everything inlcuding (REDCap Admin)
If you type a name and hit enter without clicking on the username, you will still be able to add the name you typed but it will not be a user. It will be just text that is not attached to a user. For example, I can add “Fake User” to a project:
Notice how the user list does not have a name for this person:
Make sure the user you added has a username and name in parenthesis after they are added.