title: Permission denied for usergroups.users.update
body: <p>I'm trying to add a user to a usergroup (and by that trying to use the API call usergroups.users.update) </p>
  
  <p>I'm using a workspace token that has the scope usergroups:write and usergroups:read (complete list: channels:read, channels:write, chat:write, groups:write, im:write, identity:read:user,  usergroups:read,  usergroups:write, users:read, users:read.email, users.profile:write)</p>
  
  <p>The payload is: </p>
  
  <pre><code>{"usergroup":"SCGM0xxxx","users":"U5W2Rxxxx"}
  </code></pre>
  
  <p>(Lower case xxxx to hide identity)</p>
  
  <p>POST from Curl:</p>
  
  <p><code>POST /api/usergroups.users.update HTTP/1.1</code></p>
  
  <p>The result from the POST request to usergroups.users.update simply returns </p>
  
  <pre><code>    {
       "ok" =&gt; false
       "error"  =&gt; "permission_denied"
       }
  </code></pre>
  
  <p>The documentation states:</p>
  
  <blockquote>
    <p>The user does not have permission to update the list of users for a
    User Group.</p>
  </blockquote>
  
  <p>Is there any other setting I need to configure to make this work? I have reinstalled the app after changing the oauth scopes. I added both usergroups:read and usergroups:write at the same time and I can use the API call <code>usergroups.list</code>.</p>