IWR1843AOP: Unable to get PA loopback working

Hi,

I want to test a processing chain by setting up the PA loopback and then checking if I get detections at the appropriate range/velocity.

I'm using the following function copied from the dfptest_setup.h in the SDK (3.06):

int32_t PALoopBackConfig(const int8_t loopBackEn, const uint16_t frequency_MHz)
{
    int32_t         retVal;
    rlRfPALoopbackCfg_t data = { 0 };
    data.paLoopbackFreq = 100U/frequency_MHz;
    data.paLoopbackEn = loopBackEn;

    /* Set PA Loop back configuration */
    retVal = rlRfSetPALoopbackConfig(RL_DEVICE_MAP_INTERNAL_BSS, &data);

    /* Check for mmWaveLink API call status */
    if(retVal != 0)
    {
        /* Error: Link reported an issue. */
        CLI_write("Error: rlRfSetPALoopbackConfig retVal=%d\n", retVal);
        return -1;
    }
    CLI_write("Debug: Finished rlRfSetPALoopbackConfig\n");

    return 0;
}

I'm calling the PALoopBackConfig function after opening and configuring the sensor and the data path, and before starting the sensor. The function returns without error.

At this point, I expect to see a target at ~9 meters (confirmed by doing the same setup via mmWaveStudio on 6843 EVK), but normal operation continues. In other words, the TX and RX path is not looped back, and I'm able to still see real targets and don't see anything at 9 meters.

Any idea of what I could be doing wrong?