Hi,
I have the following test code:

class BaseTest:
   ...

    @pytest.mark.dependency(name="one", depends=["zero"])
    def test_one(self, fixtures...):
        ...

    @pytest.mark.dependency(name="two", depends=["one"])
    def test_two(self, fixtures...):
        ...

    @pytest.mark.dependency(name="three", depends=["two"])
    def test_three(self, fixtures...):
        ...

    @pytest.mark.dependency(name="zero")
    def test_zero(self, fixtures...):
        ...

Other tests inherit from the BaseTest. Every class has its own file.

class TestSomething(BaseTest):
    @pytest.fixture(scope="module")
    def something(self):
        return "something"

I've been running python3 -m pytest -s --order-dependencies -ra -v --dist=loadfile -n auto.

The first ordering works well - zero runs before one for every class that inherits the test. But, for some reason, pytest-order is consistently putting test_three before test_two (except for one class in particular - not sure if this is a red herring or not). I'm not sure if this is a bug or some behavior that I don't understand. I can confirm the order that the tests are being run in in the verbose output. Everything runs correctly when running without xdist: python3 -m pytest -s --order-dependencies -ra -v -k something.
Happy to share more details privately if they would help.
Thanks for maintaining such a useful plugin!