Spotify API field filtering - spotify

Question

I'm trying to use field filtering to pick out specific nested fields, and it seems to me like I'm hitting a limit for nesting.
Here's the filter I'm using: items(date_added, track(name, album(artists(name))))
and here's the curl command I'm trying (built with the new developer console):
curl -X "GET" "https://api.spotify.com/v1/users/<user_id>/playlists/<playlist_id>/tracks?fields=items(date_added%2C%20track(name%2C%20album(artists(name))))" -H "Accept: application/json" -H "Content-Type: application/json"
This call works and everything looks good until it gets to the artists field. It doesn't seem to be filtering down artist fields. I just want the artist name in this case. Here's a snippet of what I'm getting back:
"items": [
{
"track": {
"album": {
"artists": [
{
"external_urls": {
"spotify": "https://open.spotify.com/artist/3t69c5VItBx3GCrnkcYHEL"
},
"href": "https://api.spotify.com/v1/artists/3t69c5VItBx3GCrnkcYHEL",
"id": "3t69c5VItBx3GCrnkcYHEL",
"name": "Imagined Herbal Flows",
"type": "artist",
"uri": "spotify:artist:3t69c5VItBx3GCrnkcYHEL"
}
]
},
"name": "Floating"
}
}...
];
As you can see, I'm getting the full artist object. Can someone help me understand why I can't filter the fields for that?