nrf51422 hardfault when disabling gpiote task

Question

Hi everybody!

Im trying to implement slave spi to bluetooth bridge.

In short, when cs line goes low, i want that one handshake line automaticaly go in busy (high) state (nBLE_RTR_PIN), and i did that througt ppi (note that SPI_nCS_INT_PIN is shorted in hardware with slaves SPIS_nCS_PIN):

#define BUSY_PPI_CHANNEL    0
#define BUSY_EVENT_ID       0
#define BUSY_TASK_ID        1

void cs_int_init(void)
{
    nrf_gpio_cfg_input(SPI_nCS_INT_PIN, NRF_GPIO_PIN_NOPULL);
    nrf_gpiote_event_configure(BUSY_EVENT_ID, SPI_nCS_INT_PIN, NRF_GPIOTE_POLARITY_HITOLO);
    nrf_gpio_cfg_output(nBLE_RTR_PIN);
    nrf_gpiote_task_configure(BUSY_TASK_ID, nBLE_RTR_PIN, NRF_GPIOTE_POLARITY_LOTOHI, NRF_GPIOTE_INITIAL_VALUE_LOW);
    
    //sd_ppi_channel_assign(BUSY_PPI_CHANNEL, &NRF_GPIOTE->EVENTS_IN[BUSY_EVENT_ID], &NRF_GPIOTE->TASKS_OUT[BUSY_TASK_ID]);   
    NRF_PPI->CH[BUSY_PPI_CHANNEL].EEP = (uint32_t)&NRF_GPIOTE->EVENTS_IN[BUSY_EVENT_ID];
    NRF_PPI->CH[BUSY_PPI_CHANNEL].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[BUSY_TASK_ID];
    nrf_gpiote_event_enable(BUSY_EVENT_ID);
    nrf_gpiote_task_enable(BUSY_TASK_ID);

    //sd_ppi_channel_enable_set(BUSY_PPI_CHANNEL);
    NRF_PPI->CHEN = (PPI_CHEN_CH0_Enabled << PPI_CHEN_CH0_Pos);
}

and line nBLE_RTR_PIN is going automatically in high state - ok. Now when mcu finish with processing/sending I want that slave (nrf51) manually notify master (so it can initiate another spi transaction) by pulling nBLE_RTR_PIN in ready (low) state:

nrf_gpiote_task_disable(BUSY_TASK_ID);  // -> but I'm getting hard fault here...
nrf_gpio_pin_write(nBLE_RTR_PIN, 0);
nrf_gpiote_task_enable(BUSY_TASK_ID);