Django Filter not function

I implemented Django Rest Framework and so far so good.
Pagination function ok and Ordering works as well as expected
But somehow filtering does not work on views.
1). djago-filters
Since it seems to be simple and flexible, I attempted use it.
By execution shell, it function as expected,
But when I call it from views.py, it does not work and simply return all results
Is there anything wrong or bug?

Ubuntu 22.04
Python 3.10.12
Django 4.2.6
django-filter 23.3
djangorestframework 3.14.0

*filters.py

import django_filters
from django_filters import rest_framework as dj_filters
from .models import Customer

class CustomerFilter(dj_filters.FilterSet):
    # exact only
    id = django_filters.NumberFilter()
    cd = django_filters.CharFilter()
    type = django_filters.CharFilter(lookup_expr="exact")
    branch_cd = django_filters.CharFilter()
    institution_cd = django_filters.CharFilter()

    # exact & icontains
    name = django_filters.CharFilter(lookup_expr="exact")
    name__icontains = django_filters.CharFilter(field_name="name", lookup_expr="icontains")
    postal_cd = django_filters.CharFilter(lookup_expr="exact")
    postal_cd__icontains = django_filters.CharFilter(field_name="postal_cd", lookup_expr="icontains")
    city = django_filters.CharFilter(lookup_expr="exact")
    city__icontains = django_filters.CharFilter(field_name="city", lookup_expr="icontains")
    phone = django_filters.CharFilter(lookup_expr="exact")
    phone__icontains = django_filters.CharFilter(field_name="phone", lookup_expr="icontains")
    
    # icontains only
    address1__icontains = django_filters.CharFilter(field_name="address1", lookup_expr="icontains")
    address2__icontains = django_filters.CharFilter(field_name="address2", lookup_expr="icontains")
    url__icontains = django_filters.CharFilter(field_name="url", lookup_expr="icontains")

    # range
    establish_date = django_filters.DateFromToRangeFilter()
    register_at = django_filters.DateTimeFromToRangeFilter()
    update_at = django_filters.DateTimeFromToRangeFilter()
    delete_at = django_filters.DateTimeFromToRangeFilter()
    number_of_employee = django_filters.RangeFilter()

    class Meta:
        model = Customer
        fields = [
            'id', 'cd', 'branch_cd', 'institution_cd', 'register_by', 'update_by', 'delete_by',
            'name', 'kana', 'type', 'postal_cd', 'ken', 'city', 'phone', 'fax', 'establish_by',
            'address1', 'address2', 'url',
            'establish_date', 'register_at', 'update_at', 'delete_at', 'number_of_employee',
        ]

I called above Customer Filter from shell and it returned filtered result
But when I called from views.py, it just return all UN-filtered data

**views.py

from rest_framework import status, views, generics, filters
from rest_framework.response import Response
from .serializers import CustomerSerializer, DepartmentSerializer
from .models import Department, Customer
from .pagination import LimitPagination
from django_filters.rest_framework import DjangoFilterBackend
from .filters import CustomerFilter

class CustomerListView(generics.ListAPIView):
    queryset = Customer.objects.all()
    serializer_class = CustomerSerializer
    filter_backends = [DjangoFilterBackend, filters.OrderingFilter]
    filterset_class = CustomerFilter         
    ordering_fields="__all__"
    filtering_fields="__all__"

**setting.py

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django_filters',
    'rest_framework',
    'customer',
]

REST_FRAMEWORK = {
    'DEFAULT_FILTER_BACKENDS': [
        'rest_framework.filters.OrderingFilter',
        'django_filters.rest_framework.DjangoFilterBackend',
    ],
    'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.LimitOffsetPagination',
}

Alternatively I attempted to use only filter function in views.py
it is very strange
**another attempt of views.py

from .pagination import LimitPagination
from django_filters.rest_framework import DjangoFilterBackend
from django.db.models import Q
from django.utils.dateparse import parse_date, parse_datetime

class CustomerListView(generics.ListAPIView):
    serializer_class = CustomerSerializer
    filter_backends = [filters.OrderingFilter]
    ordering_fields="__all__"
    filterset_fields="__all__"
        def get_queryset(self):
        logger.debug("get_queryset called")
        queryset = Customer.objects.all()
        #queryset = Customer.objects.filter(cd="00000030")
        print("Before filtering:", queryset.query)
        query_params = self.request.query_params
        # exactとicontainsを一つのループで処理
        filter_fields = [
            'id', 'cd', 'type', 'branch_cd', 'institution_cd',
            'register_by', 'update_by', 'delete_by', 'name', 'kana',
            'postal_cd', 'ken', 'city', 'phone', 'fax', 'establish_by',
            'address1', 'address2', 'url'  # icontains専用のフィールドも含める
        ]
        for field in filter_fields:
            # exact
            exact_value = query_params.get(field)
            if exact_value is not None:
                kwargs = {f"{field}": exact_value}
                queryset = queryset.filter(**kwargs)
            # icontainsフィルタ
            icontains_value = query_params.get(f"{field}__icontains")
            if icontains_value is not None:
                kwargs = {f"{field}__icontains": icontains_value}
                queryset = queryset.filter(**kwargs)
    return queryset

Execution

python manage.py shell
from django.test.client import RequestFactory
from customer.views import CustomerListView
factory = RequestFactory()
request = factory.get('/your-url/', {'cd': '00000100'}) 
view = CustomerListView()
view.setup(request)
view.get_queryset() #No print output nor logger output!!!
queryset = view.get_queryset()
queryset.query  #SQL does not contain where so no filtering SQL generated

Could you please help what is going on my view?
GPT is not smart enough to resolve this for me (**)