Current consumptio measurement while device is in System Off mode gives very unusual results

Question

Dear All,

I am trying to measure the current consumption for an application I am developing on the nRF52833 DK.

The code that I am running is the following:

int main(void)
{
    // Configure UICR_REGOUT0 register only if it is set to default value.
    if ((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) != (UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos)) {
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {}

        NRF_UICR->REGOUT0 = (NRF_UICR->REGOUT0 & ~((uint32_t)UICR_REGOUT0_VOUT_Msk)) | (UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos);

        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {}

        // System reset is needed to update UICR registers.
        NVIC_SystemReset();
    }

#if defined(CONFIG_NFCT_PINS_AS_GPIOS)
    if ((NRF_UICR->NFCPINS & UICR_NFCPINS_PROTECT_Msk) == (UICR_NFCPINS_PROTECT_NFC << UICR_NFCPINS_PROTECT_Pos)) {
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos; // Write Enable
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {}
        NRF_UICR->NFCPINS &= ~UICR_NFCPINS_PROTECT_Msk;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {}
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos; // Read-only Enable
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {}
        // UICR changes require a reset to be effective
        NVIC_SystemReset();
    }
#endif
    bool erase_bonds;

    // Initialize.
    lfclk_config();
    log_init();
    timers_init();
    power_management_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();
    peer_manager_init();
    flash_init();
    gpio_init();
    initialize_leds();
    wdt_init(WATCHDOG_TIMEOUT);
    sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
    sd_power_mode_set(NRF_POWER_MODE_LOWPWR);

    sleep_mode_enter();
}


static void sleep_mode_enter(void)
{
    ret_code_t err_code;

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}

Based on the product specification, I should be measuring something like 0.6uA (link).

Instead what I am measuring, using the Nordic PPK is 0.2uA. So I am really puzzled whether the measurement is accurate or not and what am I missing.

In order to perform the measurement, I prepared the DK, by cutting the SB40 trace and I set the 2 switches of the PPK to the DK.

So the question is why do I measure completely different values than the ones expected?