sprintf blocks stm32 program

I'm programming an STM32 microcontroller. In the code I'm just calling sprintf the way I did before and it worked then, but now it just freezes the entire program. What's the problem here?

char str[100]; 
sprintf(str, "TEMP_ADC: %d\n", 50);

I've included stdlib.h, stdio.h, math.h and string.h. The 100 char limit is more than enough.

I tried lighting LEDS above and below the sprintf() call and it's clear the program gets stuck on the sprintf(). I tried switching to snprintf() but it resulted in the same behaviour.

EDIT:

I noticed that sprintf() works when I use it before starting the DMA. If I use it after, the program freezes. Could it have something to do with casting an uint16_t array to uint32_t?

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 */

  uint16_t values[4];

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

/* Configure the peripherals common clocks */
  PeriphCommonClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_ADC1_Init();
  MX_TIM2_Init();
  MX_TIM16_Init();
  MX_MEMORYMAP_Init();
  MX_LPUART1_UART_Init();
  MX_RF_Init();
  /* USER CODE BEGIN 2 */

  char str[100];
  sprintf(str, "TEMP_ADC: %d\n", 50);
  int size = (int)((ceil(log10(50))+1+11)*sizeof(char));
  HAL_UART_Transmit(&hlpuart1, str, size, 100);
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, SET);

  HAL_ADC_Start_DMA(&hadc1, (uint32_t *)values, 4);
  uint16_t temp = 0;


  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
          HAL_Delay(1000);

        /* USER CODE END WHILE */

        /* USER CODE BEGIN 3 */
      }
      /* USER CODE END 3 */
    }