That's odd, either tracker-sparql is returning results in a different format or something else is up. Could you send me the result of executing Code: tracker-sparql -q "SELECT ?title ?artist ?url WHERE { ?song a nmm:MusicPiece . ?song nie:title ?title . ?song nmm:performer ?aName . ?aName nmm:artistName ?artist . ?song nie:url ?url . }" in a terminal?
tracker-sparql -q "SELECT ?title ?artist ?url WHERE { ?song a nmm:MusicPiece . ?song nie:title ?title . ?song nmm:performer ?aName . ?aName nmm:artistName ?artist . ?song nie:url ?url . }"
[nemo@Jolla ~]$ tracker-sparql -q "SELECT ?title ?artist ?url > WHERE { ?song a nmm:MusicPiece . ?song nie:title ?title . ?song nmm:performer ?aName . ?aName nmm:artistName ?artist . ?song nie:url ?url . }" (tracker-sparql:26443): Tracker-WARNING **: Locale '0' is not set, defaulting to C locale Results: None