@Mountain Pond, Thanks for posting in Q&A.
For your issue, could you please share with us what kind of enrollment method you are using?
If you turn on the Auto enrollment to MDM option, the device will just automatically join Intune when you perform the enrollment method, if you just turn on the Auto enrollment to MDM option and do nothing, the device will not automatically enroll in Intune, also, please check the requirements.
https://learn.microsoft.com/en-us/mem/intune/fundamentals/deployment-guide-enrollment#prerequisites
You can either use Company Portal to enroll the device into Intune or use the Bulk Enrollment enrolment method to create a provisioning package and place it in the network folder to enroll the device into Intune or Using BYOD method to enroll devices into Intune.
https://learn.microsoft.com/en-us/mem/intune/enrollment/windows-bulk-enroll
Note: the enrollment may take a few hours or overnight, and ensure your Internet is stable.
Hope above information can be helpful.
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