the problem is not a track number or the metadata
i fixed the sorting problem in the Qt Creator...

- singlealbumview.ui
- singleplaylistview.ui

i enabled the option "sortingEnabled" in Object: songList -> Class: QListWidget

- singleartistview.ui
- singleplaylistview.ui

i enabled the option "sortingEnabled" in Object: albumList -> Class: QListWidget

after this modifications all files ( albums, artists, songs, etc. ) are sorted correctly