IgnoreCall does not get ignored

Using the following code I expect the call to env.BuildSchema(fakeConn) to be ignored, instead this method is called with a null value?? Even when I configure the fakeDbConfig to return a recursive fake, still the GetConnection call returns a null value and env.BuildSchema does not get ignored.

        [Isolated]
        private static EnvironmentConfiguration GetEnvironmentConfiguration()
        {
            var fakeDbConfig = Isolate.Fake.Instance<IDatabaseConfig>();
            var fakeConn = Isolate.Fake.Instance<IDbConnection>();
            Isolate.WhenCalled(() => fakeDbConfig.GetConnection()).WillReturn(fakeConn);

            var fakeConfig = Isolate.Fake.Instance<Configuration>();
            var env = new EnvironmentConfiguration(TestEnv, fakeConfig, fakeDbConfig);

            Isolate.WhenCalled(() => env.BuildSchema(fakeConn)).WithExactArguments().IgnoreCall();
            return env;
        }

p.s. Also when I do

Isolate.WhenCalled(() => env.BuildSchema(fakeConn)).IgnoreCall();

the method still gets called, with a null value.