Web API Bug: "Check if Users Follow Playlist" endpoint only returns false

[rian290]

Using my user ID rian290 for playlists I follow only returns false, when it should return true.

Test:

Used where: On Spotify Web API website 

Playlist ID: 3cEYpjA9oz9GiPac4AsH4n

User ID: rian290 (is my actual ID, not just my display ID: https://open.spotify.com/user/rian290)

Proof of following: 

Expected result: [true]

Actual result: [false]

The only way I got a result of [true] was if I used a playlist ID of one that I made myself, not any other person's playlist:

I have tried this with other playlists I've followed from years ago, and it still returns false. I have also tried this request from my own JavaScript website but got the same result.

[Ximzend]

I've also tested this, and came to the conclusion that it only returns true when the a playlist is also publicly shown on the user's profile.

To get/check all of them, you'll need to get an access token through the authorization code flow with the required scopes. Sadly, I can't figure out which scopes.