JSON данные не выводятся, показывает пустой экран

Мое приложение должно возвращать JSON данные с моего API, но вместо этого я получаю пустой экран, при этом никаких ошибок не выводится. Пробовал парсить json данные с других источников (jsonplaceholder) в этом же приложении - все работает.

MainActivity.java

public class MainActivity extends AppCompatActivity {
    RecyclerView recyclerView;
    NetWorkService netWorkService;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        recyclerView = findViewById(R.id.recycler_view);


        netWorkService.getInstance()
                .getJSONApi()
                .getCategories()
                .enqueue(new Callback<ArrayList<Categories>>()
                {
                    @Override
                    public void onResponse(Call<ArrayList<Categories>> call, Response<ArrayList<Categories>> response)
                    {
                        if(response.body()!=null)
                        {
                            ArrayList<Categories> postList = response.body();
                            ActivityAdapter activityAdapter = new ActivityAdapter(MainActivity.this,postList);
                            recyclerView.setAdapter(activityAdapter);
                            recyclerView.setLayoutManager(new LinearLayoutManager(MainActivity.this));

                        } else
                        {
                            Toast toast = Toast.makeText(MainActivity.this,
                                    "responce = null", Toast.LENGTH_LONG);
                        }
                    }

                    @Override
                    public void onFailure(Call<ArrayList<Categories>> call, Throwable t)
                    {
                        Toast toast = Toast.makeText(MainActivity.this,
                                "Error, sorry", Toast.LENGTH_LONG);
                        t.printStackTrace();
                    }
                });
    }


}

NetWorkService.java

public class NetWorkService {

        private static NetWorkService mInstance;
        private static final String BASE_URL = "http://u99920uu.beget.tech/";
        private Retrofit mRetrofit;
    
    private NetWorkService()
        {
            mRetrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        

        public static NetWorkService getInstance()
        {
            if (mInstance==null)
            {
                mInstance = new NetWorkService();
            }
            
            return mInstance;
        }
        public JSONPlaceHolder getJSONApi ()
        {
            return mRetrofit.create(JSONPlaceHolder.class);
        }
    }

ActivityAdapter.java

public class ActivityAdapter extends RecyclerView.Adapter<ActivityAdapter.MyViewHolder> {
    ArrayList<Categories> posts;
    Context context;
    
    public ActivityAdapter(Context ct, ArrayList<Categories> pt){
        this.context=ct;
        this.posts=pt;
    }
   
    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(context);
        View view = inflater.inflate(R.layout.raw_categories, parent, false);
        return new MyViewHolder(view);
    }
    
    @Override
    public void onBindViewHolder(@NonNull ActivityAdapter.MyViewHolder holder, int position) {
        holder.tvBody.setText(String.valueOf(posts.get(position).getId()));
        holder.tvTitle.setText(posts.get(position).getTitle());
        Picasso.with(context)
                .load("https://dummyimage.com/1124x2238.jpg/ff4444/ffffff")
                .placeholder(R.mipmap.ic_launcher)
                .error(R.mipmap.ic_launcher)
                .into(holder.img);
    }

    @Override
    public int getItemCount() {
        return posts.size();
    }
    
    public class MyViewHolder extends RecyclerView.ViewHolder{
        TextView tvBody;
        TextView tvTitle;
        ImageView img;

        public MyViewHolder(View itemView){
            super(itemView);
            tvBody = itemView.findViewById(R.id.tv_body);
            tvTitle = itemView.findViewById(R.id.tv_title);
            img = itemView.findViewById(R.id.img_view);
        }

    }
}

JSONPlaceHolder.java

public interface JSONPlaceHolder {
    @GET("index.php")
    Call<ArrayList<Categories>> getCategories();
}

Categories.java

public class Categories {
    @SerializedName("albumId")
    @Expose
    private int albumId;
    @SerializedName("id")
    @Expose
    private int id;
    @SerializedName("name")
    @Expose
    private String title;
    @SerializedName("url")
    @Expose
    private String url;
    @SerializedName("description")
    @Expose
    private String thumbnailUrl;

    public int getAlbumId() {
        return albumId;
    }

    public void setAlbumId(int albumId) {
        this.albumId = albumId;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getThumbnailUrl() {
        return thumbnailUrl;
    }

    public void setThumbnailUrl(String thumbnailUrl) {
        this.thumbnailUrl = thumbnailUrl;
    }

}

Это мой json

[{"id":1,"name":"Fashion","description":"Category for anything related to fashion.","created":"2014-06-01 00:35:07","modified":"2014-05-30 18:34:33"},{"id":2,"name":"Electronics","description":"Gadgets, drones and more.","created":"2014-06-01 00:35:07","modified":"2014-05-30 18:34:33"},{"id":3,"name":"Motors","description":"Motor sports and more","created":"2014-06-01 00:35:07","modified":"2014-05-30 18:34:54"},{"id":5,"name":"Movies","description":"Movie products.","created":"2019-05-20 10:22:05","modified":"2019-08-20 10:30:15"},{"id":6,"name":"Books","description":"Kindle books, audio books and more.","created":"2018-03-14 08:05:25","modified":"2019-05-20 11:29:11"},{"id":13,"name":"Sports","description":"Drop into new winter gear.","created":"2016-01-09 02:24:24","modified":"2016-01-09 01:24:24"}]