Sometimes you have to install certain plugins on software before you use it. For whatever reason, some programs make you do this, and not every option is enabled by default.
Also, make sure you're not confusing library view with the file system view. Its very easy to make that mistake. In order to see the files in library view, they will have to be properly tagged.
I'm sure you already know this, but you do have to tell Jriver, or any other music software, where the folder(s) that you keep your music are. (and be sure to tell it to look in all the sub folders, as well).
Also, make sure you're not confusing library view with the file system view. Its very easy to make that mistake. In order to see the files in library view, they will have to be properly tagged.
I'm sure you already know this, but you do have to tell Jriver, or any other music software, where the folder(s) that you keep your music are. (and be sure to tell it to look in all the sub folders, as well).