It sounds like there was a problem with your database on update/install as that was the same problem you had with the genres. I checked back through the code and there is nothing missing there, so it must have been the sql queries to create didn't function.
To show them you will need to edit the Melody template files and add the functionality. None of our templates come with this inbuilt as there is no way of guessing how people will use it. To know what to do you will need to check out our Melody developer docs which explain our album, artist and song api and how to call the extrafields.