title: PayPal webhook all events remain pending
body: <p>When I complete a payment with PayPal using a sandbox account, webhook events are listed as "Pending" with an orange icon in the "Webhook events" section of the PayPal developer dashboard, and the log shows that the webhook has not been called. However, when using a different REST API app, the webhook call works perfectly!</p>
  
  <p>I have tried:</p>
  
  <ul>
  <li>Ensuring that currency is correctly configured</li>
  <li>Changing the "Payment Review" setting to "Off" for each sandbox account</li>
  <li>Making the app call the webhook for all events</li>
  <li>Comparing settings with the other app I made, for which the webhook does get called</li>
  <li>Checking that the webhook causes log output, so there is no error causing the lack of output</li>
  </ul>
  
  <p>What other things could be causing this difference, making webhook calls work for one app but get stuck in "Pending" for another that I created more recently?</p>