Current policies setup does not allow users from Editors user group to edit content. User does not have access to REST endpoint http://ezs.dev/api/ezp/v2/user/users/14 - 401 (Unauthorized)
There is two issues:
- new user menu in platform needs to load "self" to display your user name
- author field type loads assigned user to display name (and probably also email)
However editor does not always have access to this, and in legacy you did not have to as this was just fetched in templates and did not go over API which checks permissions.