Playlist API: Genres not shown

[mqrc81]

When calling the Get Playlist endpoint, according to documentation you're supposed to see an artist's genres (tracks.items.track.artists.genres), however this value is always missing.

For any given track's artist you could call the Get Artist endpoint and it will then show the genres associated with that artist, which were previously missing for the playlist endpoint.

Am I missing something or is this a bug?