GPIO (output) freezes when running ADC and DMA in continuous mode (on stm32f411) - dma

Question

I want to read 3 ADC channels (A0, A1, A2) and if the output goes below 2000 steps, B7 will be set to (1) and my LED will turn on.
I wrote a simple code to read ADC with DMA in continuous mode.
when I set to disable the DMA Continouos Request in CubeMX everything is OK.
But when I put it on Enabled, B7 or PC13 freezes and does not change bu ADC is OK.
I used STM32F411CEU blackpill
My Code :
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "adc.h"
#include "dma.h"
#include "gpio.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "stdlib.h"
#include "math.h"
#include "string.h"
#include "stdint.h"
#include "stdio.h"
uint32_t read_adc[6],buffer[3];
int i=0;
uint32_t buffer_tx;
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
for (int i=0; i<3; i++)
{
read_adc[i] = buffer[i];
}
}
/* USER CODE END 0 */
/**
* #brief The application entry point.
* #retval int
*/
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_DMA_Init();
MX_ADC1_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_SET);
HAL_Delay(1000);
HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET);
HAL_Delay(1000);
HAL_ADC_Start_DMA(&hadc1, buffer, 3);
HAL_Delay(200);
for(i=0; i<3; i++)
{
sprintf(buffer_tx,"%u",read_adc[i]);
}
HAL_ADC_Stop_DMA(&hadc1);
if(read_adc[0] < 2000)
{
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_7, GPIO_PIN_SET);
HAL_Delay(200);
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_7, GPIO_PIN_RESET);
}else
{
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_7, GPIO_PIN_RESET);
HAL_Delay(200);
}
}
/* USER CODE END 3 */
}