Hi @MARVIN, AMY L
I understand that you are encountering an issue with Delegate access in Classic Outlook application. Based on my research, this issue might be related to Outlook being unable to correctly retrieve delegate information, or to corrupted or hidden Outlook rules within the mailbox.
To troubleshoot this issue, you could try to clean up any corrupted or unexpected Outlook rules or force a refresh of the delegate data by updating it through Outlook on the Web (OWA).
You can refer more via: Can't view the Delegates page in classic Outlook for Microsoft 365 - Microsoft Support
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