Android onStop() called late while animation is in progress in back stack activity

Question

Android onStop() not called too late after finish Activity B. + It works fine under Android 7.0 Nougat.

If Animation is started from onResume and canceled from onPause, it works fine. But I wonder why.

Log below

Activity B : onPause
Activity A : onStart
Activity A : onResume
... after 10 seconds ...
Activity B : onStop
Activity B : onDestroy

Activity A : start animation

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final ImageView imageview = (ImageView) findViewById(R.id.imageview);
    final Animation anim = AnimationUtils.loadAnimation(MainActivity.this, R.anim.animation);
    imageview.setAnimation(anim);
    anim.start();

    // startActivity after about 10 seconds
    startActivity(new Intent(this, ActivityB.class);
}

Activity B : onStop is called about 10 seconds after onPause is called.

protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
    }