MusicDataRequest responding with an Internal Service Error when creating a playlist folder

I am trying to create a new playlist folder in Apple Music using MusicKit on iOS 16. However, I am receiving an Internal Service Error when sending the request.

This is the code:

let urlString = "https://api.music.apple.com/v1/me/library/playlist-folders"
let url = URL(string: urlString)!

let body = LibraryPlaylistFolderCreationRequest(
    attributes: .init(
        name: "test-playlist-folder"),
    relationships: .init(
        parent: .init(
            data: [.init(id: "playlistsroot", type: "library-playlist-folders")])))

var urlRequest = URLRequest(url: url)
urlRequest.httpMethod = "POST"
urlRequest.httpBody = try JSONEncoder().encode(body)

let request = MusicDataRequest(urlRequest: urlRequest)
let response = try await request.response()

let responseString = String(data: response.data, encoding: .utf8)
print(responseString)

When I print the request body using the following code snippet, I get the output as seen below:

let jsonBody = try JSONEncoder().encode(body)
print(String(data: jsonBody, encoding: .utf8))

Output of the above snippet:

Optional("{\"attributes\":{\"name\":\"test-playlist-folder\"},\"relationships\":{\"parent\":{\"data\":[{\"id\":\"playlistsroot\",\"type\":\"library-playlist-folders\"}]}}}")

Which should conform to the JSON scheme provided in the docs: https://developer.apple.com/documentation/applemusicapi/libraryplaylistfoldercreationrequest

And this is the error output:

[DataRequesting] Failed to perform MusicDataRequest.Context(
  url: "https://api.music.apple.com/v1/me/library/playlist-folders",
  currentRetryCounts: [.other: 1]
) with MusicDataRequest.Error(
  status: 500,
  code: 50000,
  title: "Internal Service Error",
  detailText: "",
  id: "VK23VIZ6AAM5IVP4GIFQ6VXPLU",
  originalResponse: MusicDataResponse(
    data: 111 bytes,
    urlResponse: <NSHTTPURLResponse: 0x000000028042b0c0>
  )
).

After a lot of trial and error, I don't think I know what the underlying issue is. Is MusicDataRequest not designed to issue POST requests? Is it something else?

Kind regards!