Open up The Order Exchange dashboard and look for orders that have a status of ISSUE
Open the order by double clicking it, then go to the 'Files' Tab
You can the right click on any file and choose view. In the case above you will see the file received, the data posted to the REST call (REQUEST) and the returned result from the REST call (RESPONSE).
Once the issue has been fixed the document can be resent to the ERP by going back to the dashboard, right clicking the order, and choosing "Send Order"