Can't delete attachment on a forward draft using Graph API using shared mailbox

Question

I'm trying to create a forward of an email received through a shared account, but removing any attachment the original email had.

I can create the forward draft with the API call:

POST /1.0/users/{email}/messages/{message_id}/createForward

After that, I get the list of attachments for the draft with a call to GET:

GET /1.0/users/{email}/messages/{draft_message_id}/attachments

Both calls work correctly, returning the expected data. I even can see the created forward in the Draft folder of the shared mailbox.

But when I try to delete the attachments, it fails. The API call is:

DELETE /1.0/users/{email}/messages/{draft_message_id}/attachments/{attachment_id}

The attachment_id is taken from the GET message.

The response is 503 - Service Unavailable, with this content (i've edited the mailbox id):

{
  "error": {
    "code": "ErrorMailboxMoveInProgress",
    "message": "Mailbox move in progress. Try again later., Cross Server access is not allowed for mailbox d15xxxxx-xxxx-xxxx-xxxx-xxxxx4dce97c"   }
}

If I manually add an attachment and try to remove it, it works. This only happens for attachments that were present in the original email. Issuing a send API call works fine, sending the email, but with the attachments.