Unable to add songs to collaborative playlist from the Spotify Web API

[milindmadhukar]

Plan

Free

Country
India

Operating System

(Pop OS, Linux)

My Question or Issue

Hey there, I am working on an app which lets users select songs and add to playlists.

I am a collaborator in a playlist, owned by another account.
I can add songs from the Spotify app on my Desktop or Mobile.
However when I try to add song via the Spotify Web API with the Oauth scopes: 
"playlist-read-collaborative",
"playlist-modify-public",
"playlist-read-private",
"playlist-modify-private"
It gives me the following response back
```
{
    "error" : {
        "status" : 403,
        "message" : "You cannot add tracks to a playlist you don't own."
    }
}
```

Why is that I cannot add songs from the API when I can add it from the apps?