FakeItEasy failed assertion with randomly

I'm trying to implement a unit test with a methodcall assertion. (MustHaveHappened)

I'm using the following code:

[Fact]
        public void Should_set_setting_and_map_new_value_for_non_existing_setting()
        {
            //Arrange
            var userSetting = new SettingDetailsBuilder().Build();
            var respository = A.Fake<ISettingsRepository>();
            A.CallTo(() => respository.GetUserSetting(0, 0, null)).WithAnyArguments().Returns(userSetting);
            var dataretriever = new SettingsDataRetriever(respository);

            //Act
            var newUserSetting = dataretriever.SetUserSetting("variableName", "SomeOtherValue", 1, 1, "FST");

            //Assert
            A.CallTo(() => respository.GetUserSetting(1, 1, "variableName")).MustHaveHappened();
        }

But I get randomly a failed test, whereby some arguments are mentioned as "ignored". However, the assertion is with exact parameters.

Error:

Assertion failed for the following call:
    AlfaProNext.Repositories.Settings.ISettingsRepository.GetUserSetting(1, <Ignored>, <Ignored>)
  Expected to find it at least once but found it #0 times among the calls:
    1: AlfaProNext.Repositories.Settings.ISettingsRepository.Exists(varName: "variableName")
    2: AlfaProNext.Repositories.Settings.ISettingsRepository.GetUserSetting(
          userId: 1,
          profileId: 1,
          variableName: "variableName")

Does anybody knows why this is happening randomly?