Navigating back to FragmentPagerAdapter -> fragments are empty

I had the same problem. The solution for me was simple:

in onCreateView I had:

// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(getActivity()
    .getSupportFragmentManager());

where SectionPageAdapter is something like this:

class SectionsPagerAdapter extends FragmentPagerAdapter {
...
}

after changing getSupportFragmentManager to

mSectionsPagerAdapter = new SectionsPagerAdapter(getChildFragmentManager());

it started working!