title: MS Graph does not grant access to allowExternalSenders from groups REST endpoint if application authentication is used
body: <p>I'm working on a Office 365 Groups Lifecycle tool. The app is registered with the new App V2 model and got admin consent in the related tenant.
  Here is the permissions info from the azure portal -> Azure AD -> Enterprise Apps List:</p>
  
  <ul>
  <li>Api Name: Microsoft Graph
  
  <ul>
  <li>Type: Application</li>
  <li>Permission: Read and write directory data</li>
  <li>Granted Through: Admin consent</li>
  </ul></li>
  <li>Api Name: Microsoft Graph
  
  <ul>
  <li>Type: Application</li>
  <li>Permission: Read and write all groups</li>
  <li>Granted Through: Admin consent</li>
  </ul></li>
  <li>Api Name: Microsoft Graph
  
  <ul>
  <li>Type: Application</li>
  <li>Permission: Read all users' full profiles</li>
  <li>Granted Through: Admin consent</li>
  </ul></li>
  </ul>
  
  <p>The following call URI is <a href="https://developer.microsoft.com/en-us/graph/docs/api-reference/beta/resources/group" rel="nofollow noreferrer">working as documented</a> with Graph Explorer but not with my console application using the app id and app secret:</p>
  
  <pre><code>https://graph.microsoft.com/beta/groups/{id}/allowExternalSenders
  </code></pre>
  
  <p>I would also expect that the property would return in while accessing the group but the property is not part of the JSON object return.</p>
  
  <pre><code>https://graph.microsoft.com/beta/groups/{id}
  </code></pre>
  
  <p>Accessing the property URL returns the following error message:</p>
  
  <p>Error:</p>
  
  <pre><code>response = {
    StatusCode: 403, 
    ReasonPhrase: 'Forbidden', 
    Version: 1.1, 
    Content: System.Net.Http.StreamContent, 
    Headers:
      {
        Transfer-Encoding: chunked
        request-id: a01205ec-dcc3-41cf-afc5-4943abac65aa
        client-request-id: a01205ec-dcc3-41cf-afc5-4943abac65aa
        x-...
  </code></pre>
  
  <p>Also, attempting to update the property is failing from the app but working from Graph Explorer (using a <code>PATCH</code> request).</p>
  
  <p>I found some GitHub issues related the property. Due to the reporting, the documentation was updated and no longer states a <code>PATCH</code> request can update this property: GitHub <a href="https://github.com/microsoftgraph/microsoft-graph-docs/issues/762" rel="nofollow noreferrer">Issue</a> &amp; <a href="https://github.com/microsoftgraph/microsoft-graph-docs/pull/778" rel="nofollow noreferrer">Pull Request</a></p>
  
  <p>I need to read and write this property. The documentation is at the moment saying this is read-only but I can read and write in Graph Explorer. I cannot however read and write via my app. </p>
  
  <ol>
  <li><p>What is needed to read the property? It is documented and should work right? Also as an app!</p></li>
  <li><p>When will I be able to write this property?</p></li>
  </ol>