MSP430FR2311: UART Simple Echo example with CCS using LaunchPad

Part Number: MSP430FR2311

I am having trouble with a simple UART echo wiring pins 1.6 and 1.7 together. I put this code together from various examples. When I step through the code, I can confirm that transmission is complete by the fact that the transmit interrupt is invoked (UCTXCPTIFG). When I configure the interrupt to be UCRXIFG and step through the code, the receive interrupt is never invoked. I am using CCS 9.0.1.00004  only. Here is my code:

#include <msp430.h>
#include <stdint.h>

#define    ENABLE_PINS     0xFFFE    // Required to use inputs and outputs



/**
 * main.c
 */
int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer

    P1DIR   = BIT0;                  // Make P1.0 an output for red LED
    P1OUT   = 0x00;                  // Red LED initially off

    // Configure UART pins
    P1SEL0 |= BIT6 | BIT7;      // set 2-UART pin as second function

    // Unlock GPIO
    PM5CTL0 &= ~LOCKLPM5;

    // Configure one FRAM waitstate as required by the device datasheet for MCLK
    // operation beyond 8MHz _before_ configuring the clock system.
    FRCTL0 = FRCTLPW | NWAITS_1;

    __bis_SR_register(SCG0);    // disable FLL
    CSCTL3 |= SELREF__REFOCLK;  // Set REFO as FLL reference source
    CSCTL0 = 0;                 // clear DCO and MOD registers
    CSCTL1 &= ~(DCORSEL_7);     // Clear DCO frequency select bits first
    CSCTL1 |= DCORSEL_5;        // Set DCO = 16MHz
    CSCTL2 = FLLD_0 + 487;      // set to fDCOCLKDIV = (FLLN + 1)*(fFLLREFCLK/n)
                                //                   = (487 + 1)*(32.768 kHz/1)
                                //                   = 16 MHz
    __delay_cycles(3);
    __bic_SR_register(SCG0);                        // enable FLL
    while(CSCTL7 & (FLLUNLOCK0 | FLLUNLOCK1));      // FLL locked

    CSCTL4 = SELMS__DCOCLKDIV | SELA__REFOCLK;

    // Configure UART
    // From User's Guide Table of Baud Rates, 9600 baud at BRCLK = 16000000
    // UCBRx = 104;
    // UCBRSx = 0xD6
    // UCOS16 = 1
    // UCBRFx = 2
    // Fractional portion = 0.1667
    // User's Guide Table 21-5: UCBRSx = 0xD6
    // UCBRFx = 2
    UCA0CTLW0 |= UCSWRST;
    UCA0CTLW0 |= UCSSEL__SMCLK;
    UCA0BRW = 104;
    UCA0MCTLW = 0xD600 | UCOS16_1 | UCBRF_2;
    UCA0CTLW0 &= ~UCSWRST;                  // Initialize eUSCI

    // Source = ACLK = 32768 Hz, divided by 16 (2048 Hz)
    SYSCFG2 |= RTCCKSEL;                    // Select ACLK as RTC clock
    RTCCTL = RTCSS_1 | RTCSR | RTCPS__16;

    UCA0IE  = UCTXCPTIFG;             // Interrupt when RX received
    UCA0TXBUF = 0x56;

    _BIS_SR(GIE);

    while (1);


}


#pragma vector=USCI_A0_VECTOR
__interrupt void port1_ISR(void)
{
    if(UCA0RXBUF > 0x25)
    {
        P1OUT = BIT0;                    // Turn on the red LED
    }
    else
    {
        P1OUT = 0x00;
    }
    UCA0IFG = UCA0IFG & (~UCTXCPTIFG);      // Clear TX ComPleTe Interrupt FlaG
    UCA0TXBUF = 0x56;
}