RecyclerView showing only 1st item, when tying to set dynamic height

Question

I'm trying to set the dynamic height for my recycler view, because I have the Add button below it, that adds a new item to the list.

I'm using Constraint Layout in my parent fragment. I followed this advice, and when I add first item, it shows up and the ADD button slides down as expected, but the problem is that when I add the second one it just doesn't appear.

Here is the layout of my parent fragment:

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:context=".SecondFragment">

    <Button
        android:id="@+id/cancel_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="444dp"
        android:text="@string/cancel"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/cancel_button2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/addItemActionButton" />

    <Button
        android:id="@+id/cancel_button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="76dp"
        android:text="@string/ok"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintLeft_toRightOf="@id/cancel_button"
        app:layout_constraintTop_toBottomOf="@+id/addItemActionButton"
        app:layout_constraintVertical_bias="1.0" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="372dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        app:layout_constrainedHeight="true"
        app:layout_constraintBottom_toTopOf="@id/addItemActionButton"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.41"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.065" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/addItemActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="492dp"
        android:clickable="true"
        android:src="@android:drawable/ic_input_add"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/recyclerView"
        tools:ignore="SpeakableTextPresentCheck" />
</androidx.constraintlayout.widget.ConstraintLayout>

And here's the one for the recycler item layout:

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:padding="8dp"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_constrainedHeight="true">

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/textInputLayout"
        android:layout_width="288dp"
        android:layout_height="51dp"
        android:layout_marginBottom="5dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.495"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.024">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/item"
            android:layout_width="300dp"
            android:layout_height="71dp"
            android:hint="@string/item" />
    </com.google.android.material.textfield.TextInputLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

Here's my fragment code:

package com.example.progresstracker

import android.os.Bundle
import android.util.Log
import android.util.Log.INFO
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.navigation.fragment.findNavController
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.progresstracker.databinding.FragmentSecondBinding

/**
 * A simple [Fragment] subclass as the second destination in the navigation.
 */
class SecondFragment : Fragment() {

    private var layoutManager: RecyclerView.LayoutManager? = null
    private var adapter: RecyclerView.Adapter<RecyclerAdapter.ViewHolder>? = null
    private var _binding: FragmentSecondBinding? = null
    private var items: ArrayList<String> = ArrayList()

    // This property is only valid between onCreateView and
    // onDestroyView.
    private val binding get() = _binding!!

    override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {

        _binding = FragmentSecondBinding.inflate(inflater, container, false)
        return binding.root

    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        binding.recyclerView.apply {
            // set a LinearLayoutManager to handle Android
            // RecyclerView behavior
            layoutManager = LinearLayoutManager(activity, RecyclerView.VERTICAL, false)
            // set the custom adapter to the RecyclerView
            adapter = RecyclerAdapter(items)
        }

//        linearLayoutManager = LinearLayoutManager(context)
//        binding.recyclerView.layoutManager = linearLayoutManager

        binding.cancelButton.setOnClickListener {
            findNavController().navigate(R.id.action_SecondFragment_to_FirstFragment)
        }

        binding.addItemActionButton.setOnClickListener {
            items.add("Testing..")
            adapter = RecyclerAdapter(items)
            adapter?.notifyItemInserted(items.size - 1)
            binding.recyclerView.adapter = adapter
        }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

And the adapter:

package com.example.progresstracker

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView

class RecyclerAdapter(private val items: ArrayList<String>) : RecyclerView.Adapter<RecyclerAdapter.ViewHolder>()  {

    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        var item: TextView

        init {
            item = itemView.findViewById(R.id.item)
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val v = LayoutInflater.from(parent.context).inflate(R.layout.recyclerview_item_row, parent, false)
        return ViewHolder(v)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.item.text = items[position]
    }

    override fun getItemCount(): Int {
        return items.size
    }




}