Hello GUILLOUOlivier-5426,
Thank you for posting in our Q&A forum.
You can try to disable UAC on Domain Controller to see if it helps.
Here is a similar thread with more discussion for your references.
https://social.technet.microsoft.com/Forums/en-US/729179f4-fb17-4c87-860f-227463364ef8/can-you-allow-mmcaduc-snapin-for-a-domain-user-on-a-domain-controller
Hope the information above is helpful.
Best Regards,
Daisy Zhou
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