pytest-xdist --dist=loadscope mode does not group by class

I have 2 remote servers and a master server, I send the test cases to those 2 remote servers with socket way and below is the test case ranning detail.

I want to group test cases by class and this class only runs on a remote server, so I use dist mode: loadscope, but I find that it does not work!

You can see below, the class TestStaffManagement ran by gw0 and gw1!!!

[gw1] FAILED test_cases/staff/test_department.py::TestDepartment::test_create_department
[gw1] SKIPPED test_cases/staff/test_department.py::TestDepartment::test_search_department
[gw1] SKIPPED test_cases/staff/test_staff.py::TestStaffManagement::test_search_staff
[gw0] FAILED test_cases/staff/test_staff.py::TestStaffManagement::test_create_staff
[gw1] FAILED test_cases/staff/test_staff.py::TestStaffManagement::test_export_staff
[gw0] PASSED test_cases/staff_group/test_staff_group2.py::TestStaffGroupManagement::test_default_UI
[gw1] PASSED test_cases/staff/test_staff.py::TestStaffManagement::test_create_staff_batch
[gw0] PASSED test_cases/staff/test_department.py::TestDepartment::test_default_UI

Reproduce the reported behavior with pytest-xdist using --dist=loadscope and the shown class-based tests. Start by tracing how loadscope assigns test nodes to workers, then compare the worker assignments with the expected class grouping. Done means every test from a class is scheduled on one remote worker.