Thanks for your reply, Stephen. In view of your suggestions, I have tried the following:
1. Updated MB to version 3.2.6902 (and then to 3.3 6962) and deleted all my music from the MB library and the computer.
2. Ripped one track with multiple artists.
3. Changed the ‘&’ in the Artist field to a semi-colon and checked that MB had correctly split the Artists.
4. With the Thumbnail Browser in the Left Main Panel and set to ‘Album’ 'Group By >’ ‘Artist’, I clicked on the Artist grouping, ‘George Michael; Mutya Buena’, in the Thumbnail Browser.
5. MB didn’t display the track in the main panel. (It does if I click on the Album thumbnail directly below the Artist group header.)
I tried other CDs, but the result was the same.
I did two other tests:
1. I manually added ‘George Michael; Mutya Buena’ to the splitter (it already contained the split artists). I then clicked on the Artist grouping, ‘George Michael/Mutya Buena’, in the Thumbnail Browser as before, but MB still didn’t display the track in the main panel.
2. I changed the Artist delimiter to a forward slash instead of a semi-colon. MB didn’t automatically split the artists, but did so when I clicked the ‘Split’ button. I manually added ‘George Michael/Mutya Buena’ to the splitter. MB then worked correctly and displayed the track in the main panel when I clicked on the Artist grouping, ‘George Michael/Mutya Buena’, in the Thumbnail Browser.
I would welcome any comments or suggestions. Thanks again.