Further to my initial report I realised that I had not tried to find the CDs manually using alternative identifiers so I tried to do a find using the Discogs option using Title and Artist manually and lo and behold despite having not rebooted again it found the relevant data record without incident and I added it to my catalogue of CDs. Consequently I then tried to do a UPC search using the Barcode Scanner and an autofind on Discogs and it worked perfectly. I then added another 10 or so other CDs...
Cannot lookup releases on Discogs using the online Music Search and a Barcode Scanner