Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Global Admin2,
Good day!
Thank you for posting to Microsoft Community. We are happy to help you.
Based on your description i can understand that you have archive mailbox issues for a mailbox that's migrated to or from Microsoft 365. So far what i know there are five scenario that are related to archive mailboxes. This issue occurs generally if a mailbox is migrated between an on-premises Exchange Server environment and Exchange Online.
Please read this KB: Archive mailbox issues for a mailbox that's migrated to or from Microsoft 365 - Office 365 | Microsoft Learn
If your issue is related to this scenario: you can't migrate on-premises archive mailboxes to Microsoft 365 in hybrid migration. please check below steps.
Since we are not in same environment where i can reproduce the issue and provide the details steps for the resolution, you can post your issue in our dedicated team for hybrid environment. You can be assist accurately. Microsoft Exchange Hybrid Management - Microsoft Q&A
Please feel free to let us know if there are any questions or if we've got you wrong. We will keep assisting you based on the information you provide. We sincerely appreciate your patience and cooperation.
Sincerely,
Eben Ezer Tres | Microsoft Community Moderator