Part of the Okta-AD Integration guide
If users from on-premises AD are missing from the import list in Okta, check the following:
First Name and Last Name attributes — Users without both a First Name and Last Name attribute populated in AD will not be imported. Open the affected user accounts in Active Directory Users and Computers and confirm both fields are populated.
Email attribute and UPN format — All users being imported should have an Email attribute populated, and the UPN format should be consistent across all users in the OU. See Prepare an OU for AD users you will import to Okta for full requirements.
OU configuration — Confirm the affected users are in an OU that has been configured for import to Okta, and that all users in that OU meet the user import requirements.
Still having trouble? Create a support ticket and our team will be happy to help.