Вложенный сериализатор Django выдает мне None для всех полей

Я работаю с Django и djangorestframework (версии 3.2.12 и 3.12.4, соответственно) и столкнулся с проблемой вложенных сериализаторов.

У меня есть модели FantasyLeague и FantasyLeagueSettings. FantasyLeagueSettings имеет FK к FantasyLeague

models.py

class FantasyLeague(models.Model):
    name = models.CharField(max_length=100)
    managers = models.ManyToManyField(User)
    yahoo_league_id = models.CharField(max_length=20, blank=True, null=True)

class FantasyLeagueSettings(models.Model):
    league = models.ForeignKey(FantasyLeague, on_delete=models.CASCADE, related_name='settings')

    max_teams = models.IntegerField(blank=True, null=True)
    num_playoff_teams = models.IntegerField(blank=True, null=True)
    playoff_start_week = models.IntegerField(blank=True, null=True)

Я сериализую их следующим образом:

serializers.py

class FantasyLeagueSettingsSerializer(serializers.ModelSerializer):
    class Meta:
        model = FantasyLeagueSettings
        fields = ['max_teams', 'num_playoff_teams', 'playoff_start_week']

class FantasyLeagueSerializer(serializers.ModelSerializer):
    managers = UserSerializer(read_only=True, many=True)    
    settings = FantasyLeagueSettingsSerializer(many=False, read_only=True)

    class Meta:
        model = FantasyLeague
        fields = ['id', 'name', 'managers', 'settings', 'yahoo_league_id' ]

Но по какой-то причине FantasyLeagueSerializer(league).data выдает мне значение None для всех полей настроек (хотя данные о настройках существуют)

Тестовый код:

    league = FantasyLeague.objects.get(pk=1)

    print('🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥')
    print(FantasyLeagueSerializer(league).data)
    # FantasyLeagueSerializer(league).data: {'id': 1, 'name': 'PLAYING FOR KEEPS', 'managers': [OrderedDict([('id', 1), ('username', 'Smurflo'), ('settings', OrderedDict([('selected_theme', 'kanagawa')])), ('is_staff', True)])], 'settings': OrderedDict([('max_teams', None), ('num_playoff_teams', None), ('playoff_start_week', None)]), 'yahoo_league_id': '461051' }
    # Note how all of the settings fields are None

    # Even though league.settings clearly has data and FantasyLeagueSettingsSerializer works
    print('🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆🎆')
    print(FantasyLeagueSettingsSerializer(league.settings.all()[0]).data)
    # {'max_teams': 12, 'num_playoff_teams': 6, 'playoff_start_week': 15}

Кто-нибудь знает, что здесь происходит? Что я упускаю?

class FantasyLeagueSerializer(serializers.ModelSerializer):
    ...
    settings = FantasyLeagueSettingsSerializer(many=True, read_only=True)
    ...

class FantasyLeagueSettings(models.Model):
    league = models.OneToOneField(FantasyLeague, on_delete=models.CASCADE, related_name='settings')
    ...