Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Dear Ytse Jam,
Good day!
Thank you for posting to Microsoft Community. We are glad to assist!
Based on your description regarding " Cannot create Mailboxes under Management Scope". As far as I know custom write scopes cannot create new objects as it doesn't match parameters of the management scope. Kindly try to use a role group with a default write scope.
Furthermore, if you are still getting this situation. I therefore believe that this issue should be further investigated by our online technical support team. A support Engineer can further connect with you remotely, for further troubleshooting and involve the backend team where need be. The team might request for your public IP address or collect some logs. Please understand that as public forum support, we don’t have higher permissions to check and analyze these logs or check the IP addresses and considering your scenario maybe inconveniencing, to quickly help assist, kindly contact your organization admin or you can create a service request to report this symptom to our online channel. Here is contact support document: Get support - Microsoft 365 admin | Microsoft Learn
Thanks for your precious time and your understanding would be highly appreciated. Have a nice day
Best regards,
Inema | Microsoft Community Moderator