The property 'Item' is required when creating the entity

Question

I encountered an error while working with the Microsoft Graph API. The error message states, "The property 'Item' is required when creating the entity."

I'm trying to auto-reply to an email that contains an item attachment, which is an EML file. However, I'm encountering issues when attempting to attach the same EML file to my reply.

Here is my code:

MessageAttachmentsCollectionPage attachmentsList = new MessageAttachmentsCollectionPage();

      if (Convert.ToBoolean(lastMail.HasAttachments))
      {
          var pageIterator2 = PageIterator<Microsoft.Graph.Attachment>
          .CreatePageIterator(
              _appMsGraphApiClient,
              lastMail.Attachments,
              (a) =>
              {
				 if (a is Microsoft.Graph.ItemAttachment itemAttachment)
                  {
                      attachmentsList.Add(itemAttachment);
                  }
                  return true;
              },
              (req) =>
              {
                  return req;
              }
          );
          pageIterator2.IterateAsync().Wait();
      }

 var replyAllMessage = new Microsoft.Graph.Message
 {
     Subject = "",
     Body = new ItemBody
     {
         ContentType = Microsoft.Graph.BodyType.Html,
         Content = ""
     }
 };

if (attachmentsList.Count > 0)
{
    replyAllMessage.Attachments = attachmentsList;
}

await _appMsGraphApiClient.Users[id].Messages[messageID]
.ReplyAll(replyAllMessage)
.Request()
.PostAsync();