Getting 'Not Found' across all routes

Describe the bug
Hello, I'm trying to run pytest-flask's live server in conjunction with selenium, but every one of my registered routes return a 404 status.
Both my app fixture and the live_server's app are the same (app == live_server.appreturns True, but I haven't checked out if they're the exact same object), and both app objects return the expected routes when calling app.url_map

It not only happens in testing: running the suite via a debugger and stopping the execution just before it fails, and visiting the app's routes in another tab or browser results in the same 404 status responses.

To Reproduce
I have the project open and available in github here, in the tests/login_example branch. Just start a virtual environment, install the requirements and run the following test:

pytest src/tests/system/guest/test_login.py

Expected behavior
The test passes.

Screenshots
Checking url_map in the debugger:

Firefox showing the error:

Environment (please complete the following information):

• OS: ArchLinux with the Linux 6.8.2 kernel
• Python Version: 3.11.8
• pytest-flask version: 1.3.0

Additional context
The test proper:

@pytest.mark.usefixtures('live_server')
class TestLogin(TestSystemBase):
    def test_correct_login(db, driver, live_server):
        driver.get(f"http://localhost:8888{url_for('sessions_controller.new')}")
        assert 'Login' in driver.page_source

My app fixture:

@pytest.fixture(scope='session')
def app():
    app = Flask(__name__)
    app.config['TESTING'] = True
    initializer.init_app(app)
    app.config['SECRET_KEY'] = secrets.token_hex(32)

    with app.app_context():
        yield app

    clear_data(app)

My selenium driver fixture:

@pytest.fixture
def driver():
    options = webdriver.FirefoxOptions()
    #options.add_argument('-headless')
    driver = webdriver.Firefox(options=options)

    yield driver

    driver.close()

Run pytest src/tests/system/guest/test_login.py from the linked tests/login_example branch, then inspect the app, live_server, and Selenium driver fixtures shown in the issue. Compare the registered routes in app.url_map with the URLs requested by the test; done means the login route and the test no longer return 404.