title: Outlook rest api "synchronize messages" ignores $expand in subsequent calls
body: <p>I am trying to synchronize an Outlook folder (say the Inbox) using the beta version of the Outlook Rest Api <a href="https://msdn.microsoft.com/en-us/office/office365/api/mail-rest-operations#Synchronizemessagespreview" rel="nofollow">see doc here</a></p>
  
  <p>I need only to retrieve the property <em>IsRead</em> and the <em>PR_INTERNET_MESSAGE_ID</em></p>
  
  <p>So following documentation, for the first synchronization my requests look like:</p>
  
  <p>The following Http headers are always added: </p>
  
  <pre><code>  request.Headers.Add("Prefer", "odata.track-changes");
    request.Headers.Add("Prefer", "odata.maxpagesize=5"); //Use a small page size easier for debugging
  </code></pre>
  
  <ol>
  <li><p>The first initial full synchronization request</p>
  
  <p><code>https://outlook.office365.com/api/beta/Me/MailFolders('inbox')/messages?$select=IsRead&amp;$expand=SingleValueExtendedProperties($filter=(PropertyId eq 'String 0x1035'))</code></p>
  
  <p><strong>Good results</strong> the <code>value</code> array contain what I need.</p></li>
  <li><p>The second request after the first request uses the <em>deltatoken</em></p>
  
  <p><code>https://outlook.office365.com/api/beta/Me/MailFolders('inbox')/messages?$select=IsRead,Subject&amp;$expand=SingleValueExtendedProperties($filter=(PropertyId eq 'String 0x1035'))&amp;$deltatoken=a758b90491954a61ad463ef3a0e690a2</code></p>
  
  <p><strong>Bad results</strong>, no SingleValueExtendedProperties entries</p></li>
  <li><p>Next requests for paginations with <em>skiptoken</em>...</p>
  
  <p><code>https://outlook.office365.com/api/beta/Me/MailFolders('inbox')/messages?$select=IsRead,Subject&amp;$expand=SingleValueExtendedProperties($filter=(PropertyId eq 'String 0x1035'))&amp;$skiptoken=e99ad10324464488b6b219ca5ed6be1c</code></p>
  
  <p><strong>Bad results</strong> again, same as 2.</p></li>
  </ol>
  
  <p>It looks like a bug to me. Can you provide a workaround? From a list of <em>ItemId</em> is possible to retrieve easily the list of corresponding <em>PR_InternetMessage_Id</em> efficiently (not item per item)?</p>
  
  <p>Note also that in the documentation it is written that:</p>
  
  <blockquote>
    <p>The response will include a Preference-Applied: odata.track-changes
    header. If you attempt to sync a resource that is not supported, this
    header will not be returned in the response. Check for this header
    before processing the response to avoid errors.</p>
  </blockquote>
  
  <p>It seems that for 2. and 3. calls this response header "Preference-Applied" is not set.</p>