Why my MLX90614ESF-DCI sensor saturates at 300°C?

Question

I have an MLX90614ESF-DCI FIR sensor to measure a metal rod temperature. Everything is fine below 300°C. But exactly at 300°, the measured temperature is saturated and doesn't show higher values. I expect to measure up to 380°C based on the information provided on the datasheet of the sensor.

Edit:

Here is the schematic of my circuit.

^{simulate this circuit – Schematic created using CircuitLab}

and the code for reading the sensor value is something like following:

#include <Adafruit_MLX90614.h>

Adafruit_MLX90614 mlx = Adafruit_MLX90614();

int status = 0;
void setup(){

Serial.begin(9600);
    if(!mlx.begin())
        status = 1;
}

void loop(){

    Serial.println(mlx.readObjectTempC());
    delay(5);
}

As I mentioned I have no issue reading the value of temperature from this sensor. The main problem is that the sensor saturates for temperatures values above 300 °C while regarding the info on datasheet I supposed to measured values up to 380 °C.