Force ExpandableListView fastScroll to iterate through all items instead of sections

Question

I'm working with a ExpandableListView and BaseExpandableListAdapter and I noticed that enabling fastScroll the scroll iterates through sections or headers. It would be great if it were not because it does not work properly. The fastScroll iterates through all sections with only a small portion of the scroll on top, just starting to scroll, and then when at the first quarter of the scroll passed and all sections are scrolled to the screen, the scroll does nothing.

Here is a demonstration gif:

I've checked this old post android fastScroll only covers part of the list, but didn't work for me.

Anyone knows another workaround to this bug or know how to force the ExpandableListView fastScroll to iterate through all items instead of sections?

Here is the example code, if it's useful for you.

activity_main.xml

<FrameLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  tools:context=".MainActivity">

  <ExpandableListView
    android:id="@+id/listview"
    android:layout_width="match_parent"
    android:fastScrollEnabled="true"
    android:layout_height="match_parent"></ExpandableListView>

</FrameLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {

 private ExpandableListView listView;

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

   ExpandableAdapter adapter = new ExpandableAdapter(this, getItems());
   listView.setAdapter(adapter);
 }

 private Map<String, List<String>> getItems() {
   Map<String, List<String>> items = new LinkedHashMap<>();
   // Loops to create stub items
   return items;
 }

 private static class ExpandableAdapter extends BaseExpandableListAdapter {

  private final Context context;
  private ArrayList<String> sections;
  private Map<String, List<String>> items;

  public ExpandableAdapter(Context context, Map<String, List<String>> items) {
    this.context = context;
    this.items = items;
    this.sections = new ArrayList<>(items.keySet());
  }

  @Override
  public int getGroupCount() {
    return sections.size();
  }

  @Override
  public int getChildrenCount(int groupPosition) {
    return items.get(sections.get(groupPosition)).size();
  }

  @Override
  public String getGroup(int groupPosition) {
    return sections.get(groupPosition);
  }

  @Override
  public String getChild(int groupPosition, int childPosition) {
    return items.get(getGroup(groupPosition)).get(childPosition);
  }

  @Override
  public long getGroupId(int groupPosition) {
    return 0;
  }

  @Override
  public long getChildId(int groupPosition, int childPosition) {
    return 0;
  }

  @Override
  public boolean hasStableIds() {
    return false;
  }

  @Override
  public View getGroupView(int groupPosition, boolean b, View view, ViewGroup viewGroup) {
    // No ViewHolder pattern because of testing purposes
    view = View.inflate(context, R.layout.row, null);
    TextView tv = view.findViewById(R.id.text);
    tv.setText(getGroup(groupPosition));
    return view;
  }

  @Override
  public View getChildView(int groupPosition, int childPosition, boolean b, View view, ViewGroup viewGroup) {
    // No ViewHolder pattern because of testing purposes
    view = View.inflate(context, R.layout.row, null);
    TextView tv = view.findViewById(R.id.text);
    tv.setText(getChild(groupPosition, childPosition));
    return view;
  }

  @Override
  public boolean isChildSelectable(int groupPosition, int childPosition) {
    return false;
  }
 }
}