When moving your datas like favorite artists, albums or songs and even playlists to Spotify, they could not be displayed immediately in your mobile / desktop Spotify app.
There's lot of cache on Spotify apps, so the first thing to do is to check on the web version of Spotify here: https://open.spotify.com/collection and for songs: https://open.spotify.com/collection/tracks
If you are able to see your datas on this web page but not on your Spotify app:
- Try to logout and login again to Spotify
- Try to clear your app cache in settings of Spotify
- Finally uninstall Spotify app and install it back
If you are not able to see your datas even on Spotify app, double check you are using the right Spotify account and try again.