I'm a Spotify user having multiple devices on many platforms.
I found out that Windows Spotify's library data inconsistency compared to my other devices.
The newest song isn't updated. Moreover, the song sets are different from other devices; some songs just missed.
Re-Login or Reinstall cannot solve the dataset inconsistency.
You have to delete this directory on Windows to make Spotify sync Library all over again (Windows 10):
%appdata%\Local\Packages\SpotifyAB.SpotifyMusic_xxxxxxxx\LocalState\Spotify/Users
ref:
Playlists not syncing between devices (Spotify Community)