Azure translator: Russian transliteration ignores capital letters

I am using the transliterate API v3.0: (https://api.cognitive.microsofttranslator.com/transliterate?api-version=3.0)
russian word 'Робот' is transliterated into 'abot'. Expected result is 'Rabot'.

code used:

    text = 'Робот'
    url = 'https://api.cognitive.microsofttranslator.com/transliterate?api-version=3.0'
    params = '&language=ru&fromScript=Cyrl&toScript=Latn'
    constructed_url = url + params
    body = [{
        'text': text
    }]
    translator_key = os.environ['AZURE_TRANSLATOR_KEY']
    region = 'eastus'
    headers = {
        'Ocp-Apim-Subscription-Key': translator_key,
        'Ocp-Apim-Subscription-Region': region,
        'Content-type': 'application/json',
        'X-ClientTraceId': str(uuid.uuid4())
    }    
    request = requests.post(constructed_url, headers=headers, json=body)
    response = request.json()

    print(response)

Returns: [{'text': 'abot', 'script': 'Latn'}]