spi_transceive() writes zero into the buffer in runtime

Question

Hello everyone, I am working with a BMI160 6-DoF sensor. I have some drivers related to this chip. Using the Segger J-Link debugger the drivers just work fine without any issues I am able to read the data registers on the sensor via SPI interface. 
 uint8_t getData_bmx160(bmx160_spi * bmxIMU_spi_p, bmx160_sensor_data * sen_data)
{
...
 uint8_t data[12] = {0,0,0,0,0,0,0,0,0,0,0,0};
 result = readReg_bmx160(bmxIMU_spi_p, BMX160_GYR_X_LSB_REG, data, 12);
...
}

int readReg_bmx160(bmx160_spi * bmxIMU_spi_p, uint8_t reg, uint8_t *data, size_t len)
{
 int result;
	unsigned char tx_buffer[2] = { 0, 0};

tx_buffer[0] = 0x80 | reg;

const struct spi_buf tx_buf = {
 .buf = tx_buffer,
 .len = 1,
	};
	const struct spi_buf_set tx = {
 .buffers = &tx_buf,
 .count = 1,
	};

struct spi_buf rx_buf[2] = {
 {
 .buf = tx_buffer,
 .len = 1,
 },
 {
 .buf = data,
 .len = len,
 }
	};

const struct spi_buf_set rx = {
 .buffers = rx_buf,
 .count = 2,
	};
	gpio_pin_set(bmxIMU_spi_p->gpio0_dev, bmxIMU_spi_p->spi_cs_pin, 1);
	result = spi_transceive(bmxIMU_spi_p->spi_dev, &bmxIMU_spi_p->spi_cfg, &tx, &rx);
 gpio_pin_set(bmxIMU_spi_p->gpio0_dev, bmxIMU_spi_p->spi_cs_pin, 0);

if (result) {
 return result;
	}

return 0;
} 
 
 This is how the registers are read on the driver. However, when I switch to the runtime the 'data' is not updated even though 'spi_transceive(..)' returns >= 0 .