Dictionary with OrdinalIgnoreCase fails

Running the following code from visual studio/stand alone always returns "Success" (which is the expected result), but after putting it through SA 6.9 (settings do not matter) it always returns "FAILURE".

private void Test()
        {
            if (!TestDictionary.ContainsKey("AÜ"))
            {
                MessageBox.Show("FAILURE");
            }
            else
            {
                MessageBox.Show("Success");
            }
            Environment.Exit(-1);
        }

        public static Dictionary<string, int> TestDictionary = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase) { { "Aü", 1 } };