John, sound has nothing much to do with CVs.
If your upload fails, the decoder's sound archive will be corrupted and probably be unplayable. You need to keep trying with your upload.
Fails are most often due to to poor contact so if you're relying on wheels on track first make sure these are scrupulously clean. If the uploads still fail you may need to look at making a direct connection, ie, a wired one.
Your comment about the sound files pane is more worrying because it displays the PROJECT not what's in the decoder.
If it is blank the PROJECT is corrupted, so get a new download then check the sound files pane again. The sound files have got to be there for a successful upload.
Peter
