title: Mailchimp API "Marketing permission ID '' does not exist." while passing valid id
body: <p>I use the Mailchimp API to first get the marketing_permission_id for my list. The response looks like this</p>
  
  <blockquote>
    <p>[marketing_permission_id] => f878932739</p>
  </blockquote>
  
  <p>This value is then used in a second api call to update the settings for a specific user. However, I get the error:</p>
  
  <blockquote>
    <p>string(227)
    "{"type":"<a href="http://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/" rel="nofollow noreferrer">http://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/</a>","title":"Bad
    Request","status":400,"detail":"Marketing permission ID '' does not
    exist.", [...]</p>
  </blockquote>
  
  <p>I double checked the data that is being send in the second call and it has the correct marketing_permission_id in there:</p>
  
  <pre><code>{"marketing_permissions":{"marketing_permission_id":"f878932739","enabled":true}} 
  </code></pre>
  
  <p>I followed the format from <a href="https://developer.mailchimp.com/documentation/mailchimp/reference/lists/members/#%20" rel="nofollow noreferrer">https://developer.mailchimp.com/documentation/mailchimp/reference/lists/members/#%20</a>.</p>
  
  <p>I don't understand what's going wrong. Hopefully someone here does.. :)</p>