Songs disappeared from playlist bit not from preview

[Step4ever]

Hello everyone!
2 days ago I created a playlist with the 3 albums of Charlie Winston. Today the playlist still indicates that it has 40 songs in it but once I click on it, only 12 are remaining (last album and few songs from previous ones). The strange thing is that the songs that has disappeared are still displayed in the preview and are available on open spotify... So can't be a rights problem?

Anyone has a clue?