Imgur API GET request always returns 404 page in Android but works in POSTMAN

Question

This is driving me insane. I am trying to do a very simple GET request to the Imgur API to get the images from an album as per their API https://apidocs.imgur.com/#3606f862-8281-48f1-b0f7-49a5f77da0e1

It works perfectly well in Postman, but whatever method I try to do a GET request in Android I always get a 404 page. An actual HTML page at that, not an API formatted JSON response. Here is the code I have been running inside an AsyncTask.

This is the version with OkHttp:

OkHttpClient client = new OkHttpClient();

        Request request = null;
        try {

            request = new Request.Builder()
                    .url(new URL("https://api.imgur.com/3/album/6BUjs/images?v=4"))
                    .method("GET", null)
                    .addHeader("Authorization", "Client-ID " + clientId)
                    .addHeader("Content-Type", "application/json")
                    .addHeader("Accept", "application/json")
                    .addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36")
                    .build();
        } catch (MalformedURLException e) {
            Log.e("OKHttpError", e.getMessage());
            return null;
        }
        try {
            Response response = client.newCall(request).execute();
            return response.body().string();
        } catch (IOException e) {
            Log.e("OKHttpError", e.getMessage());
            return null;
        }

This is the version with Unirest

        HttpResponse<String> response = null;
        Unirest.setTimeouts(0, 0);
        Unirest.clearDefaultHeaders();
        try {
            response = Unirest.get("https://api.imgur.com/3/album/6BUjs/images?v=14")
                    .header("Authorization", ("Client-ID " + clientId))
                    .header("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36")
                    .header("Content-Type", "application/json")
                    .header("Accept","application/json")
                    .asString();

        } catch (UnirestException e) {
            Log.e("HTTP Exception", e.getMessage());
        }
        return response.getBody();

And this is the version with HttpURLConnection

 try {
            URL url = new URL("https://api.imgur.com/3/album/6BUjs/images");
            HttpURLConnection http = (HttpURLConnection)url.openConnection();
            http.setRequestMethod("GET");
            http.setDoOutput(true);
            http.setRequestProperty("Authorization", "Client-ID " + clientId);
            http.setRequestProperty("Accept", "application/json");
            http.setRequestProperty("Content-Type", "application/json");
            http.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36");

            return http.getResponseCode() + " " + http.getResponseMessage();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }

Here is the full class file for reference:

public class ImgurAlbumAPIClass extends AsyncTask<String, Void, String> {
    String clientId = "5070e3bc69f6159";

    @Override
    protected String doInBackground(String... strings) {

        OkHttpClient client = new OkHttpClient();

        Request request = null;
        try {

            request = new Request.Builder()
                    .url(new URL("https://api.imgur.com/3/album/6BUjs/images?v=4"))
                    .method("GET", null)
                    .addHeader("Authorization", "Client-ID " + clientId)
                    .addHeader("Content-Type", "application/json")
                    .addHeader("Accept", "application/json")
                    .addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36")
                    .build();
        } catch (MalformedURLException e) {
            Log.e("OKHttpError", e.getMessage());
            return null;
        }
        try {
            Response response = client.newCall(request).execute();
            return response.body().string();
        } catch (IOException e) {
            Log.e("OKHttpError", e.getMessage());
            return null;
        }

    }

    @Override
    protected void onPostExecute(String body) {
        Log.d("ImgurAPI", body);
    }
}

It really is a very simple class with a very simple goal. I have been rocking my brain. Any help is appreciated!!!