Saving of _factory doesn't apear, if run few test at once

Hi! I fetched strange behaviour, most probably the bag, that I resolved, but it shouldn't be. That you can see under a comments

@pytest.fixture()
def hundred_provider_stocks(provider_stock_factory):
    provider_stock_factory.create_batch(10)


@pytest.mark.django_db
@pytest.mark.parametrize('browser', [lazy_fixture("partner_browser_client"), lazy_fixture("client")])
@pytest.mark.parametrize('page', [('products-detail', [1]), ('products-list', [])])
def test_get_serializer_class(browser, page, hundred_provider_stocks):
    page = browser.get(reverse(page[0], args=page[1]))
    assert page.status_code == 200


@pytest.mark.django_db(transaction=True)
def test_notify_about_providerstock_change(provider_stock_factory, demand_factory, personal_subscription_factory,
                                           product, mailoutbox, celery_worker):
    d = demand_factory(individual_demands=[product])
    personal_subscription_factory(demand=d)
    p = provider_stock_factory(product=product)
    p.save() # If I don't type this, mail, that should be sent each time, when object is changing, is not sending, if I run all test at one time in module. So I have only 1 mail in my mailoutbox. But it works good if I run only test_notify_about_providerstock_change. 
    p.price = 1000
    p.save()
    logging.info(mailoutbox[0].body)
    assert len(mailoutbox) == 2

And second question is that I wanted to do @pytest.fixture(scope="session" or "module") on hundred_provider_stocks but I got error

ScopeMismatch: You tried to access the function scoped fixture provider_stock_factory with a module scoped request object, involved factories:
goods\test_app.py:13:  def hundred_provider_stocks(provider_stock_factory)
venv\lib\site-packages\pytest_factoryboy\fixture.py:493:  def fn(request: 'SubRequest', *, factory_class: 'F' = <class 'keysbilling.factoryboy_fixtures.ProviderStockFactory'>) -> 'F'

This solution doesn't work for me
https://stackoverflow.com/questions/51783757/pytest-scopemismatch-error-how-to-use-fixtures-properly

Start with goods\test_app.py, especially test_get_serializer_class and test_notify_about_providerstock_change, and reproduce them together and individually. Compare the fixture-scope failure with the provider_stock_factory traceback in site-packages\pytest_factoryboy\fixture.py; done means isolating whether the mail behavior and ScopeMismatch are pytest-django issues and defining the expected behavior.