Certain playlists won't sync when adding new songs

[marengs92]

Plan

Premium

Country

Norway

Device 

iPhone 6s

Operating System

iOS 12.0.1 

My Question or Issue

 Hi,

I am having trouble with playlists that will not sync, this happens regularly to certain playlists. I add songs, but they do not show up in the lists. Sometimes they show up for some days, but then they disappear, and might appear again randomly. I am almost always using Spotify from my iPhone, and always add songs to playlists through my phone. I have tried logging on / off, setting the app to offline mode etc., but nothing seems to work.

Would really appreciate som help on this, my favourite playlists are useless when they are outdated!