Hi @User Admin,
Thank you for posting your question in the Microsoft Q&A forum.
Based on your inquiry, we understand that you have configured user's category tags to your company's shared mailbox, but they seem to disappear or not activate.
According to your issue, the user's tag may concern to Microsoft Defender configuration. As forum moderators, we don’t have access to the detailed system needed to troubleshoot this effectively due to privacy and security constraints. I suggest you raise a support ticket from the Microsoft 365 admin center, where the related team can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem.
If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Note: To create a support ticket, you need to have Microsoft 365 admin privileges and if you aren’t admin of your organization, please contact the admin of creating a new ticket.
In the meantime, I have found this article, and I think you can try to configure this tag more effective:
User tags in Microsoft Defender for Office 365 - Microsoft Defender for Office 365 | Microsoft Learn
We hope this information is helpful and appreciate your understanding.
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