hi,team:

    my dag is 1 minute schedule,one parts dag state is success,but tasks state is not yet started in a dag:

![image](https://user-images.githubusercontent.com/41068725/116344664-357d8780-a819-11eb-8010-c746ffdfdbcc.png)


   how can to fix it?
tests/www/test_app.py
@dont_initialize_flask_app_submodules(skip_all_except=['init_appbuilder'])
    def test_flask_cli_should_display_routes(self, capsys):
        with mock.patch.dict("os.environ", FLASK_APP="airflow.www.app:cached_app"), mock.patch.object(
            sys, 'argv', ['flask', 'routes']
        ), pytest.raises(SystemExit):
            runpy.run_module('flask', run_name='__main__')
        output = capsys.readouterr()
        assert "/login/" in output.out