Thank you for reaching out through the Microsoft Q&A forum.
If you're experiencing issues adding or removing devices despite having the correct permissions, it could be related to the group's membership type. To resolve this, please try changing the Membership type to "Assigned". This change should allow you to manually manage the devices in the group.
If the issue persists after making this change, we recommend reaching out to Microsoft Intune Support through the Microsoft Endpoint Manager admin center for further assistance.
We hope the details provided will assist you effectively.
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