@Cantata Admin,Thanks for posting in Q&A.
According to your description, I know that you want to enroll existing Azure AD devices into Intune.
Based on my researching, I found that to enroll existing Azure AD joined devices to Intune, there are some methods you can try:
- Option 1: Group Policy. (Local Group Policy)
- Option 2. Registry
- Option 3. PowerShell
https://call4cloud.nl/2020/05/intune-auto-mdm-enrollment-for-devices-already-azure-ad-joined/
Nonofficial, just for reference.
Meanwhile, please ensure the Microsoft Intune licenses and Azure AD Premium license are assigned. And the MDM user scope under Automatic enrollment is set as all.
Enable MDM automatic enrollment for Windows | Microsoft Learn
Hope this can be helpful.
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