If users are not appearing in Oak through Entra ID synchronisation, there are a few things to check.
Make sure each user has a valid and unique email address, as this is required to create their account. Usernames must also be unique.
Check for duplicate area names under the same parent area. For example, if a department and location have the same name, Oak may be unable to create the required areas or users.
Finally, make sure the user is within a tracked Organisational Unit (OU) in Entra ID. Only users in tracked OUs can be created or updated during synchronisation. Tracked OUs can be managed under Site Settings > OIS.