MSP430FR5739: TA0R does not increment when TA0CCTL0 is set to capture mode

I find that TA0R does not increment when I set CAP = 1. 

First I set up TA0 along with TB1 and TB2, and start them closely together:

            // Configure P2.3 as CCI0B input for TA0CCR0 capture
            P2SEL0 |= BIT3;
            P2SEL1 &= ~(BIT3);
            P2DIR  &= ~(BIT3);

            // Set time base to source from same clock as everything else
            TA0CTL |= TASSEL__ACLK | ID__8;
            // Setup TA0CCR0 for:
            //      -- Capture on both rising/falling edges ( CM_3 )
            //      -- Select CCI0B (P2.3) as the capture input pin
            //      -- Synchronize captures to clock ( .SCS bit / bit 11  )
            //      -- Enables capture mode ( .CAP bit / bit 8 ) = 1
            TA0CCTL0 |= CM_3 | CCIS_1 | BIT8 | BITB;

            // After all configuration is done, enable the CCR0 capture interrupt
            TA0CCTL0  |= CCIE;

I also configure TB1/TB2 ( just to show clocks/timers are running )

TB1CCR0 = 62500;
TB2CCR0 = 62500;

TB1CCTL0 |= CCIE;
TB2CCTL0 |= CCIE;

Then I start all three timers TA0, TB1, TB2:

    // Start the actual timers ...
    TB2CTL   = TBSSEL__ACLK | ID__8 |  MC__UP;
    TB1CTL   = TBSSEL__ACLK | ID__8 |  MC__UP;
    TA0CTL   = TASSEL__ACLK | ID__8 |  MC__UP;

    // Then reset timers to all start at 0
    TB2CTL |= TBCLR;
    TB1CTL |= TBCLR;
    TA0CTL |= TACLR;

When I observe TA0CTL & TA0CCTL0 in a debug environment, it seems everything is set up correctly like in my code:

It seems like TA0R never increments!  And I cannot figure out why this is so when TACTL0 is configured correctly. To show that ACLK is running as well as TB1/TB2:

When I input a pulse into P2.3 / CCI0B, the interrupt is triggered and the program enters the ISR I can tell it enters the ISR because I put a breakpoint inside of it:

#pragma vector = TIMER0_A0_VECTOR
__interrupt void Timer0_A0_ISR(void)
{
    __no_operation(); // Breakpoint on this line
    myBufferValue = TA0CCR0;
}

However, since TA0R never increments, the value of myBufferValue  is always zero. 

What am I doing wrong here? Why does TA0R never increment despite UP_MODE being selected?  From the status bits in TA0CTL / TA0CCTL0 it seems configured as per the manual.