RecyclerView inside TabHost only refresh when tab change

I am using a TabHost with TabWidget and inside a ViewPager. For the ViewPager I created my FragmentPagerAdapter and inside I put some Fragments. In every Fragment I have a RecyclerView to display information vertical and horizontal.

The Fragment is updating when I change from one tabwidget but not when the Activity is loaded.

Graphics Behaviour

For example I check my products list I pickup on I buy this product and then in other tab the list of my products should be listed but it doesn't, when I change the tab and return to my previous tab then the view is update and the products list is showing.

Ok here is the first tab where I select a product, In tab One, I have a ViewPager with a FragmentPagerAdapter. The list of products is a RecyclerView. When I select a Product, an Activity is launch then I buy the product.

When I buy the product I return to my main Activity (TabHost container) I and should see the product bought in the list but the list is empty.

When I change the tab and return to list tab then fragment is showed. I don't know here is my error.

Code of main Activity

It is my main activity code:

public class AppTabActivity extends AppCompatActivity
        implements ViewPager.OnPageChangeListener,
        TabHost.OnTabChangeListener {

public static final String TAB_INDEX = "TAB_INDEX";
ViewPager pager;
TabPagerAdapter tabsPagerAdapter;
TabHost tabHost;
Toolbar topToolBar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.app_main_layout);

    topToolBar = (Toolbar) findViewById(R.id.idTopToolBar);
    setSupportActionBar(topToolBar);

    tabHost = (TabHost) findViewById(android.R.id.tabhost);
    tabHost.setup();

    String[] tabNames = getResources().getStringArray(R.array.tabs_name);
    for (String tab : tabNames) {
        TabHost.TabSpec tabSpec;
        tabSpec = tabHost.newTabSpec(tab);
        tabSpec.setIndicator(tab);
        tabSpec.setContent(new FakeView(getApplicationContext()));
        tabHost.addTab(tabSpec);
    }
    tabHost.setOnTabChangedListener(this);

    pager = (ViewPager) findViewById(R.id.viewPager);

    if(tabsPagerAdapter == null )
        tabsPagerAdapter = new TabPagerAdapter(getSupportFragmentManager());
    pager.setAdapter(tabsPagerAdapter);
    tabsPagerAdapter.notifyDataSetChanged();
    pager.addOnPageChangeListener(this);

    Intent from = getIntent();
    //when i buy a product i send the tab list index of my bought products
    int currentIndex = from.getIntExtra(TAB_INDEX, 1);
    pager.setCurrentItem(currentIndex);

}

@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

}

@Override
public void onPageSelected(int position) {
    tabHost.setCurrentTab(position);
    pager.setCurrentItem(position);
    tabsPagerAdapter.notifyDataSetChanged();
}

@Override
public void onPageScrollStateChanged(int state) {

}

@Override
public void onTabChanged(String tabId) {
    int selectedItem = tabHost.getCurrentTab();
    pager.setCurrentItem(selectedItem);
}

class FakeView implements TabHost.TabContentFactory {

    Context context;

    public FakeView(Context ctx) {
        context = ctx;
    }

    @Override
    public View createTabContent(String name) {

        View view = new View(context);
        view.setMinimumHeight(0);
        view.setMinimumWidth(0);
        return view;
    }
}
}

TabPagerAdapter

I use a list of my Fragments.

public class TabsPagerAdapter extends FragmentPagerAdapter  {

List<Fragment> fragmentList;

public TabsPagerAdapter(FragmentManager fm) {
    super(fm);
    fragmentList = new ArrayList<>();
    fragmentList.add(new ProductFragment());
    fragmentList.add(new BuyListFragment());
    fragmentList.add(new DetailFragment());
}

@Override
public Fragment getItem(int position) {
    return fragmentList.get(position);
}

@Override
public int getCount() {
    return fragmentList.size();
}

@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}
}

Tips

Each fragment implements its view using a layout. The layouts contains some widgets and one of them are RecyclerView. I only share the TabHost, ViewPager and Adapter code because I think the problem is here, When I change the tabs the list is paint. I am lost, I don't know were is the problem.