Azure App Permission for Get-RecipientPermission

I have defined an Azure App with read only permission for unattended script use to monitor and report on Azure AD accounts and Mailboxes (Users and Shared). A script I am working on to facilitate user offboarding is to remove delegated mailbox access for leavers. I am trying to retrieve delegated mailbox access details and I am having an issue with permission to run Get-RecipientPermission (Get-EXORecipientPermission).

If I Connect manually using Connect-Exchangeonline with Admin creds. the permissions are retrieved successfully.

If I connect using certificate based auth' (Connect-Exchangeonline -appid $appid -organization $orgName -certificatethumbprint $certthumb), I can retrieve mailbox detail but not the delegated permission. I receive a permission error.

$TrusteeMailbox = Get-Mailbox "SharedMaibox" | get-exorecipientpermission | Where-Object {$_.trustee -eq $LeaverUPN}

get-exorecipientpermission : Error while querying REST service. HttpStatusCode=401 ErrorMessage={"error":{"code":"Unauthorized","message":"User is not allowed

to call Get-RecipientPermission","innererror":{"message":"User is not allowed to call

Get-RecipientPermission","type":"Microsoft.Exchange.Admin.OData.Core.ODataServiceException"}}}

At line:1 char:52

+ ... = Get-Mailbox "SharedMaibox" | get-exorecipientpermission | Where ...

+ ~~~~~~~~~~~~~~~~~~~~~~~~~~

*+ CategoryInfo          : ProtocolError: (:) [Get-EXORecipientPermission], RestClientException*

*+ FullyQualifiedErrorId : An error occurred while processing this request.,Microsoft.Exchange.Management.RestApiClient.GetExoRecipientPermission*
```Azure registered App permissions are:

![User's image](/api/attachments/b091554a-2849-4f7b-a1a6-4cc2c9204827?platform=QnA)

What App permission is required to retrieve the delegated permission?

Any Help much appreciated.

Mark