Can't reorder playlist mac

[Thierrydriessen]

as of today, I can't reorder my playlists on my Mac, it says something about duplicate tracks and when I add anyway it duplicates instead of moving the song up or down the list. Also I can't delete the songs from my playlist. 

I'm tired of all the problems I have had with Spotify, I'm Sorry but if there is not a solution to this, I am very affraid that I will stop using Spotify completely.

Thanks for all the help,

Thierry