How to load data into a RecyclerView inside a fragment using ViewModel

I am trying to create a app with bottom navigation, that switches between several fragments.

Inside one of these I need to list data in a recyclerview. I am rather new to android and I have never used a recyclerview or used ViewModels or fragments before so I am not 100% sure if I am doing this the right way.

Here is what I have right now:

Fragment.java

public class twoFragment extends Fragment implements LifecycleOwner {

    private twoViewModel twoViewModel;
    private RecyclerView recyclerView;
    private RecyclerViewAdapter recyclerViewAdapter;

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {


        twoViewModel = new ViewModelProvider(this).get(twoViewModel.class);
        View root = inflater.inflate(R.layout.two, container, false);

        recyclerView = root.findViewById(R.id.rv_main);
        recyclerView.setHasFixedSize(true);

        twoViewModel.getUserMutableLiveData().observe(getViewLifecycleOwner(), userListUpdateObserver);


        return root;
    }

        private Observer<ArrayList<User>> userListUpdateObserver = new Observer<ArrayList<User>>() {
            @Override
            public void onChanged(ArrayList<User> userArrayList) {

                recyclerViewAdapter = new RecyclerViewAdapter(requireActivity(),userArrayList);
                recyclerView.setAdapter(recyclerViewAdapter);
            }
        };

}

ViewModel.java

public class twoViewModel  extends ViewModel {

    MutableLiveData<ArrayList<User>> userLiveData;
    ArrayList<User> userArrayList;

    public twoViewModel() {
        userLiveData = new MutableLiveData<>();

        // call your Rest API in init method
        init();
    }

    public MutableLiveData<ArrayList<User>> getUserMutableLiveData() {
        return userLiveData;
    }

    public void init(){
        populateList();
        userLiveData.setValue(userArrayList);
    }

    public void populateList(){

    User user = new User();
        user.setTitle("Darknight");
        user.setDescription("Best video ever!");

        userArrayList = new ArrayList<>();
        userArrayList.add(user);
        userArrayList.add(user);
        userArrayList.add(user);
        userArrayList.add(user);
        userArrayList.add(user);
        userArrayList.add(user);

}



}

RecyclerViewAdapter.java

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    Activity context;
    ArrayList<User> userArrayList;

    public RecyclerViewAdapter(Activity context, ArrayList<User> userArrayList) {
        this.context = context;
        this.userArrayList = userArrayList;
    }


    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View rootView = LayoutInflater.from(context).inflate(R.layout.item,parent,false);
        System.out.println("onCreateViewHolder");
        return new RecyclerViewViewHolder(rootView);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {

        User user = userArrayList.get(position);
        RecyclerViewViewHolder viewHolder= (RecyclerViewViewHolder) holder;

        viewHolder.txtView_title.setText(user.getTitle());
        viewHolder.txtView_description.setText(user.getDescription());
        viewHolder.imgView_icon.setImageDrawable(user.getImgIcon());
        System.out.println("onBindViewHolder");
    }

    @Override
    public int getItemCount() {
        return userArrayList.size();
    }

    class RecyclerViewViewHolder extends RecyclerView.ViewHolder {
        ImageView imgView_icon;
        TextView txtView_title;
        TextView txtView_description;

        public RecyclerViewViewHolder(@NonNull View itemView) {
            super(itemView);
            imgView_icon = itemView.findViewById(R.id.imgView_icon);
            txtView_title = itemView.findViewById(R.id.txtView_title);
            txtView_description = itemView.findViewById(R.id.txtView_description);
            System.out.println("RecyclerViewViewHolder");

        }
    }
}

The problem

With this code, the recyclerview is empty when I open the app. However, when I click on the EditText view that I have in the fragment the data appears in recyclerview. Then, as soon as I leave the fragment and go back to it, it is empty.

What am I doing wrong here?

I read somewhere you are not supposed to use ViewModels and recyclerviews together...how does that work?