From the 'Search' tab, search by 'Supplier'. This will show all the requests for this supplier and their status. The list can be restricted further by selecting a 'Status' in the search criteria.
To resolve this, log out of Batch Returns and log back in again or press Ctrl F5 to refresh the browser and the labels should be available by searching for the required RAN and going to the Confirmation screen from where the labels or a picking list can be printed.
A request has been started for that supplier, but it hasn't been sent. You need to complete that request before starting another one for the same supplier.