Playlist API not returning deeply nested field

[eeeevrsince]

I want to fetch user playlist items (tracks mainly) and for each track it's authors and for each author genres and images. This is the fields query parameter: `items.track(id,name,artists(id,name,genres,images))`. But API isn't returning "deeply nested" fields past artists (see response screenshot below)

Here is `curl` request copied from Web API reference:

```

curl --request GET \
--url 'https://api.spotify.com/v1/playlists/3cEYpjA9oz9GiPac4AsH4n/tracks?fields=items.track%28id%2Cname%2C...' \
--header 'Authorization: Bearer <token>'

```

This is probably a bug since example fields argument `items(added_by.id,track(name,href,album(name,href)))` fetches fields to the "same" depth (although artists is an array of objects)