How do we get SAPI or IPA phoneme results for en-GB for a pronunciation assessment?

Hi,

So I am trying to use the Speech Service that Azure AI Speech provides. I want to use the pronunciation assessment feature from the speech-to-text functionality. Here below is the code I used:

def speech_recognize_with_pronuncation(filePath, text_script):
    referenceText = text_script if text_script else "" 
    speech_config = speechsdk.SpeechConfig(subscription=config("SPEECH_KEY"), region=config("SERVICE_REGION"))
    speech_config.speech_recognition_language="en-GB"
    audio_config = speechsdk.audio.AudioConfig(filename=filePath)
    
    speech_recognizer = speechsdk.SpeechRecognizer(
        speech_config=speech_config, 
        audio_config=audio_config
    )

    pronunciation_config = speechsdk.PronunciationAssessmentConfig(json_string="{{\"referenceText\":\"{}\",\"gradingSystem\":\"HundredMark\",\"granularity\":\"Phoneme\",\"phonemeAlphabet\":\"IPA\"}}".format(referenceText))

    pronunciation_config.enable_prosody_assessment() 
    pronunciation_config.enable_content_assessment_with_topic("greeting")
    pronunciation_config.apply_to(speech_recognizer)

    speech_recognition_result = speech_recognizer.recognize_once()

    pronunciation_assessment_result_json = speech_recognition_result.properties.get(speechsdk.PropertyId.SpeechServiceResponse_JsonResult)

    return pronunciation_assessment_result_json

The problem I am facing is that the phonemes that are getting returned after analysis are empty. However, the accuracy scores are available for the empty phonemes. Here below is the response showing empty phonemes but with score values:

{
    "status_code": 200,
    "message": "Successful",
    "detail": {
        "Id": "d954ca5f17f54eb9a36978c67211b4fc",
        "RecognitionStatus": "Success",
        "Offset": 800000,
        "Duration": 4000000,
        "Channel": 0,
        "DisplayText": "Heart.",
        "SNR": 46.816277,
        "NBest": [
            {
                "Confidence": 0.91353595,
                "Lexical": "heart",
                "ITN": "heart",
                "MaskedITN": "heart",
                "Display": "Heart.",
                "PronunciationAssessment": {
                    "AccuracyScore": 42.0,
                    "FluencyScore": 100.0,
                    "ProsodyScore": 0.0,
                    "CompletenessScore": 100.0,
                    "PronScore": 28.4
                },
                "Words": [
                    {
                        "Word": "heart",
                        "Offset": 800000,
                        "Duration": 4000000,
                        "PronunciationAssessment": {
                            "AccuracyScore": 42.0,
                            "ErrorType": "Mispronunciation",
                            "Feedback": {
                                "Prosody": {
                                    "Break": {
                                        "ErrorTypes": [
                                            "None"
                                        ],
                                        "BreakLength": 0
                                    },
                                    "Intonation": {
                                        "ErrorTypes": [],
                                        "Monotone": {
                                            "SyllablePitchDeltaConfidence": 0.50218755
                                        }
                                    }
                                }
                            }
                        },
                        "Syllables": [
                            {
                                "Syllable": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 800000,
                                "Duration": 4000000
                            }
                        ],
                        "Phonemes": [
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 800000,
                                "Duration": 1300000,
                                "blend_shape": []
                            },
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 2200000,
                                "Duration": 500000,
                                "blend_shape": []
                            },
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 2800000,
                                "Duration": 700000,
                                "blend_shape": []
                            },
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 3600000,
                                "Duration": 1200000,
                                "blend_shape": []
                            }
                        ]
                    }
                ],
                "Incorrect_spoken_words": [
                    {
                        "Word": "heart",
                        "Offset": 800000,
                        "Duration": 4000000,
                        "PronunciationAssessment": {
                            "AccuracyScore": 42.0,
                            "ErrorType": "Mispronunciation",
                            "Feedback": {
                                "Prosody": {
                                    "Break": {
                                        "ErrorTypes": [
                                            "None"
                                        ],
                                        "BreakLength": 0
                                    },
                                    "Intonation": {
                                        "ErrorTypes": [],
                                        "Monotone": {
                                            "SyllablePitchDeltaConfidence": 0.50218755
                                        }
                                    }
                                }
                            }
                        },
                        "Syllables": [
                            {
                                "Syllable": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 800000,
                                "Duration": 4000000
                            }
                        ],
                        "Phonemes": [
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 800000,
                                "Duration": 1300000,
                                "blend_shape": []
                            },
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 2200000,
                                "Duration": 500000,
                                "blend_shape": []
                            },
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 2800000,
                                "Duration": 700000,
                                "blend_shape": []
                            },
                            {
                                "Phoneme": "",
                                "PronunciationAssessment": {
                                    "AccuracyScore": 42.0
                                },
                                "Offset": 3600000,
                                "Duration": 1200000,
                                "blend_shape": []
                            }
                        ]
                    }
                ]
            }
        ]
    }
}

Please address this issue ASAP since this featue is crucial in my project and our use for this feature will be huge.

Thank you
Umair Habib