title: INVALID_ENCRYPTED_ID when trying to get invoice details
body: <p>Using the /v1/invoicing/invoices/invoice_id API in the PayPal Sandbox to retrieve invoice information, I am getting the following error no matter which invoice I use:</p>
  
  <pre><code>{
  "name": "INVALID_ENCRYPTED_ID",
  "message": "Invalid encrypted id",
  "information_link": "https://developer.paypal.com/docs/api/invoicing/#errors",
  "debug_id": "c64c84ba18ede",
  "details": [{
          "error_code": "27"
      }
  ]
  </code></pre>
  
  <p>}</p>
  
  <p>I have tried other APIs such as creating an invoice, sending an invoice, etc and they all work fine with the same credentials.</p>
  
  <p>I can't find any mention of this error anywhere on PayPal or using Google.</p>
  
  <p>Any ideas?  Thanks!</p>