Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi sir,
We cannot set the Office 365 Business account address as the alias of @outlook.com account. It should be related to the known issue which the support mentioned.
In this situation, I suggest you contact the @outlook support to move on the issue as it is related to Microsoft account, not Office 365 Business.
You may post a new thread in the community under category outlook.com (click the link below):
Regards,
Hans