Read ADC using internal voltage reference in STM32L422KB

I am STM32L422 to measure ADC using internal reference voltage.

My code is generated using CubeMX V6.2.

I want to measure ADC from ADC1_IN1 using PA7.

The data sheet says internal voltage is 1.2 V. Reading VREFINT register gave value 1658 which is 1.214 V from 3v full scale.

My maximum voltage input is 3V. It is connected to ADC in through 20k/10k voltage divider.

3V *10/30 = 1V

But I get 0.595 V.

If Vref = 1.2, then I should get 1.2 V in Vref pin but Vref pin voltage is 0.535 volt.

To enable internal reference voltage, I have checked Vrefint Channel in ADC

int main(void)
{
 /* USER CODE BEGIN 1 */
 
 /* USER CODE END 1 */
 
 /* MCU Configuration--------------------------------------------------------*/
 
 /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
 HAL_Init();
 
 /* USER CODE BEGIN Init */
 
 /* USER CODE END Init */
 
 /* Configure the system clock */
 SystemClock_Config();
 
 /* USER CODE BEGIN SysInit */
 
 /* USER CODE END SysInit */
 
 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_ADC1_Init();
 MX_SPI1_Init();
 MX_USART1_UART_Init();
 MX_USART2_UART_Init();
 MX_TIM6_Init();
 MX_RTC_Init();
 /* USER CODE BEGIN 2 */
 
	
// =======================================================================================================
 printf("VREFINT: %ud\n", VREFINT);	
	while(HAL_ADCEx_Calibration_Start(&hadc1,0) != HAL_OK);
 
// =======================================================================================================
	printf("Battery Voltage Check ...\n");
 
	HAL_Delay(100);
	HAL_ADC_Start(&hadc1);
	HAL_ADC_PollForConversion(&hadc1,100);
	ADC_Val=HAL_ADC_GetValue(&hadc1);
	HAL_ADC_Stop(&hadc1);
	 
	float Result = (float)((1.200 * ADC_Val) / 4095); 
	
	printf("Digital: %d, Result Value : %f	\r\n", ADC_Val, Result );
	
 /* USER CODE END 2 */
 
 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 ;
 }
}

My initialization code is generated using CubeMX V6.2.

What is the problem here ?