Troubleshooting access permissions for functional accounts

Check if You Are Using Nested Groups to Assign Delegate Access

Check in your source whether nested groups are used to assign delegate access to the functional account.

For example, the group support-agents can be part of the group support-team. The group support-team is assigned to the functional account support@example.com, where support-agents contains the members john.doe@example.com and jane.doe@example.com.

- support@example.com (shared mailbox)
|   - support-team (group)
|   |   - support-agents (group)
|   |   |   - john.doe@example.com (user mailbox)
|   |   |   - jane.doe@example.com (user mailbox)

Are you using nested groups?