@PRK Thanks for posting in our Q&A. From your description, I know that enroll only in device management setting is missing in the windows 10 device. If there is any misunderstanding, feel free to let us know.
In my research, enroll only in device management setting is available in OS Build 14393.82 (Windows 10 1607 with KB3176934) and later. We can see more details in the following link. So we suggest to check the version of our Windows 10 device. If it is lower than the required version, we suggest to upgrade to later version.
https://learn.microsoft.com/en-us/windows/client-management/mdm/mdm-enrollment-of-windows-devices#connect-to-mdm-on-a-desktop-enrolling-in-device-management
Hope it can help.
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