Are you getting this ? none of the selected files could be converted because they could not be found itunes
To fix it just logout of iTunes and exit it then go back in then log back in and it should now convert your songs. You welcome.....
Question marked as
Sometimes the work around above don't work so I found out if you highlight one of the tracks in the album then press Ctrl+A to select all the convert option will pop up and convert the album. You welcome!