Unable to change mailbox permissions

Thanks for your comments.

There are other people indicating this is an issue that Microsoft need to resolve, but just to clarify, in a hybrid environment where the mailboxes have been migrated to M365, managing delegation and permission to mailboxes should be done in Exchange Admin Centre in M365?

Just checking because some online documentation suggests you have to do it on-prem using powershell which seems a bit strange?

Just to clarify, these are the errors we get:

When trying to edit permissions in M365 we either get:

Or if we try in powershell we get:

Get-EXOMailboxPermission : An error occurred while processing this request.. {"error":{"code":"Unauthorized","message":"User is not allowed to call Get-MailboxPermission","innererror":{"message":"User is not allowed to call Get-MailboxPermission","type":"Microsoft.Exchange.Admin.OData.Core.ODataServiceException","stacktrace":""

Thanks for the reply. There are other people having the similar issues.

But just to clarify, once a mailbox is migrated from on prem to M365, (even thought the hybrid setup is still in place), the permissions/delegates changes should be able to be made via the Exchange Admin Centre in M365?

I just ask because some resources say you still have to manage the mailbox in M365 from the on prem Exchange Server or the on prem Powershell console?

Thanks