So for anyone coming across this at a later stage...
I finally manage to fix this by creating a new instance of the fragment and restoring it's state using a Fragment.SavedState
object. So:
if (mSummaryFragment.isAdded() && mDetailsFragment.isAdded()) {
Fragment.SavedState sumState = getSupportFragmentManager().saveFragmentInstanceState(mSummaryFragment);
Fragment.SavedState detState = getSupportFragmentManager().saveFragmentInstanceState(mDetailsFragment);
mSummaryFragment = new SummaryFragment();
mSummaryFragment.setInitialSavedState(sumState);
mDetailsFragment = new DetailsFragment();
mDetailsFragment.setInitialSavedState(detState);
}
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.add(R.id.summary_container, mSummaryFragment);
ft.add(R.id.details_container, mDetailsFragment);
ft.commit();
I do not understand why this works and the old method doesn't, however this may be helpful for someone else.