When requesting a user object via WSAPI, not all of the user object attributes are visible.
For example, the following request is missing numerous fields such as DefaultProject, EmailNotificationEnabled, LastActiveDate and many more:
For security reasons, this can happen when the user making the request does not have sufficient access levels to view these privileged fields.
Make the request using a user ID with higher security permissions. At a minimum, Workspace Administrator permissions are needed to view these additional fields.