Not all my liked songs are in the Liked Songs Playlist

[burryport]

Plan

Premium

Country

UK

Device

Laptop and Samsung Galaxy 8

Operating System

Android Oreo, Windows 10

My Question or Issue

I have a Favourite Songs playlist with every song liked.  It has 2878 songs in it.  My Liked Songs Playlist only has 1520.  Why are all of my liked songs not in the Liked Songs Playlist and how do I rectify it?

Similarly not all my albums are in the Albums playlist and not all my artists are in the Artist playlist.

Without the ability to create smart playlists like on iTunes you'd think the default "smart" playlists would actually work.