TMS320F28379D: EPWM - double pulse generation

I am trying to use the EPWM module to generate double pulse waveforms for driving a power FET test rig. Based on my understanding of this controller family, the appropriate way to do this is in software using interrupts (ie INT_EPWMx) that are triggered by the timebase counter being equal to some CMPx - this should correspond to a rising or falling edge of the PWM waveform.

I am currently stuck on getting two pulses of different widths to repeat in a periodic fashion (pulse 1 has width a, and pulse 2 has width b). I am trying to do this by changing the duty cycle of the EPWM back and forth from one value to another. Forcing the EPWM low for isolated double pulses is a problem I will solve later - probably via trip zone interrupts.

Here is a minimal version of the logic I would like to implement - this is based on the epwm_ex11_configure_signal example in c2000 ware.

#include "driverlib.h"
#include "device.h"
#include "board.h"

uint32_t  epwm1IntCount;

EPWM_SignalParams pwmSignal1 =
            {10000, 0.5f, 0.5f, true, DEVICE_SYSCLK_FREQ, SYSCTL_EPWMCLK_DIV_2,
            EPWM_COUNTER_MODE_UP_DOWN, EPWM_CLOCK_DIVIDER_1,
            EPWM_HSCLOCK_DIVIDER_1};

EPWM_SignalParams pwmSignal2 =
            {10000, 0.25f, 0.5f, true, DEVICE_SYSCLK_FREQ, SYSCTL_EPWMCLK_DIV_2,
            EPWM_COUNTER_MODE_UP_DOWN, EPWM_CLOCK_DIVIDER_1,
            EPWM_HSCLOCK_DIVIDER_1};

//  Interrupt Prototype
__interrupt void modDutyCycle(void);

void main(void)
{
    // Initialize needed components
    epwm1IntCount = 0U;
    Device_init();
    Device_initGPIO();
    Interrupt_initModule();
    Interrupt_initVectorTable();
    Board_init();
    SysCtl_disablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);
    EPWM_configureSignal(myEPWM1_BASE, &pwmSignal1);
    // Set EPWM
    EPWM_configureSignal(myEPWM1_BASE, &pwmSignal1);
    SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);
    
    //Interrupts
    Interrupt_enable(INT_EPWM1);
    EPWM_enableInterrupt(myEPWM1_BASE);
    EPWM_setInterruptSource(myEPWM1_BASE, EPWM_INT_TBCTR_D_CMPA);
    EPWM_setInterruptEventCount(myEPWM1_BASE, 1U);
    Interrupt_register(INT_EPWM1, &modDutyCycle);
    EINT;  // Enable Global interrupt INTM
    ERTM;  // Enable Global realtime interrupt DBGM
    for(;;)
    {
        asm ("NOP");
    }
}

__interrupt void modDutyCycle(void)
{
    if (epwm1IntCount > 0U)
    {
        EPWM_configureSignal(myEPWM1_BASE, &pwmSignal1);
        epwm1IntCount = 0U;
    }
    else
    {
        EPWM_configureSignal(myEPWM1_BASE, &pwmSignal2);
        epwm1IntCount++;
    }
    EPWM_clearEventTriggerInterruptFlag(myEPWM1_BASE);
    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP3);
}

This works if I modify the duty cycle for the first time to the new value and stop cycling through the interrupts (I get pulse width b), but if I continue cycling the EPWM stops outputting any signal at all as measured on an oscilloscope. I have looked through the program flow using breakpoints in debug mode and confirmed that my EPWM_INT_TBCTR_D_CMPA is indeed being properly triggered and cleared each cycle, and that the logical flow of my program snippet is correct.

What am I missing here? Is the configure signal function in ex11 doing something I'm not aware of/something not appropriate for implementing this? This is seems to be an issue stemming from being unfamiliar with this family of controllers as opposed to a fundamental logic/programming problem.