CCS/TM4C123GH6PZ: UARTCharPut works while UARTPrintf doesn't

Tool/software: Code Composer Studio

Hello,

I'm trying to use the UART peripheral on my TM4C Launchpad to communicate with an host PC.

I use the following code:

////////////////////////////////////////////////////////////////////////////////////////////////////
#include <stdbool.h>
#include <stdint.h>
#include "driverlib/debug.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/pwm.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "inc/hw_gpio.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include <stddef.h> // For using the NULL pointer

#define PWM_FREQUENCY 55

////////////////////////////////////////////////////////////////////////////////////////////////////
// My I2C defines & includes
#include "driverlib/i2c.h"
#include "driverlib/interrupt.h"
#include "inc/hw_i2c.h"
#include "inc/hw_ints.h"
#include "sensorlib/i2cm_drv.h"
#include "sensorlib/mpu6050.h"
#include "sensorlib/hw_mpu6050.h"
#define DEBUG


////////////////////////////////////////////////////////////////////////////////////////////////////
// My UART defines & includes
#include "driverlib/uart.h"
#include "utils/uartstdio.h"

////////////////////////////////////////////////////////////////////////////////////////////////////
int main(void)
{

    // Configure the clock
    SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
////////////////////////////////////////////////////////////////////////////////////////////////////
    // My UART initialization code
    SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
    GPIOPinConfigure(GPIO_PA0_U0RX);
    GPIOPinConfigure(GPIO_PA1_U0TX);
    GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
    UARTConfigSetExpClk(UART0_BASE, SysCtlClockGet(), 115200,(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE | UART_CONFIG_PAR_NONE));

    UARTCharPut(UART0_BASE, 'X');

    UARTprintf("Y");

    while(1)
    {

    }
}

When I run the code the letter X prints correctly but the letter Y doesn't print.

What am I doing wrong?