Zephyr nrf5340 cpu app SPI1 burst read missing byte

Hi,

I am trying to burst read FIFO of ADXL362 with zephyr adxl362 sample. 1 byte tx (read fifo command) and n byte rx ( reading the fifo data);

Zephyr is the last version 3.0 , ncs is 1.9.1   , mcu is nrf5340 app s

i write this function to set a spi transaction is like this ; 

adxl362.c

#define ADXL362_READ_FIFO          0x0D
int adxl362ext_get_fifo_data(const struct device *dev,uint8_t *read_buf, uint8_t count)
{
	const struct adxl362ext_config *cfg = dev->config;
	uint8_t access[1] = { ADXL362_READ_FIFO};
volatile int i=1,m=9;
	const struct spi_buf txbuf =
	{
			.buf = access,
			.len = 1
	};

	const struct spi_buf_set tx = {
		.buffers = &txbuf,
		.count = 1
	};	

	const struct spi_buf rxbuf =	{
			.buf = read_buf,
			.len = count
	};

	const struct spi_buf_set rx = {
		.buffers = &rxbuf,
		.count = 1
	};

	return spi_transceive_dt(&cfg->bus, &tx, &rx);
}

i call it from the standard function comes with the adxl362 sample ; 

adxl362_trigger.c

uint8_t Acc_Data[400];

static void adxl362_thread_cb(const struct device *dev)
{
	struct adxl362_data *drv_data = dev->data;
	uint8_t status_buf;

	/* Clears activity and inactivity interrupt */
	if (adxl362_get_status(dev, &status_buf)) {
		LOG_ERR("Unable to get status.");
		return;
	}

	k_mutex_lock(&drv_data->trigger_mutex, K_FOREVER);
	if (drv_data->th_handler != NULL) {
		if (ADXL362_STATUS_CHECK_INACT(status_buf) ||
		    ADXL362_STATUS_CHECK_ACTIVITY(status_buf)) {
			drv_data->th_handler(dev, &drv_data->th_trigger);
		}
	}

	if (drv_data->drdy_handler != NULL &&
	    ADXL362_STATUS_CHECK_DATA_READY(status_buf)) {
		drv_data->drdy_handler(dev, &drv_data->drdy_trigger);
	}

	
	adxl362ext_get_fifo_data(dev,(uint8_t *)&Acc_Data,7);

	k_mutex_unlock(&drv_data->trigger_mutex);
}

Result is like this ; 

Debug:

I can also verify by logic analyzer 1 byte is missing from the original count. 

If i set it to 1 , i can not see any spi clocks for rx buffer.

If i set it to 6 , i can see that spi will be clocked out for 5 bytes.

I couldn't locate the code makes it from 7 to 6, or 6 to 5  or n  to n-1 .

Thanks