Grove - I2C Thermocouple Amplifier MCP9600 only reach 255°C

Hi, I have trouble with my thermocouple amplifier, it gives temperature only between 0 and 255°C.
If I have 256°C I got a 0°C and as the temperature increases it keep increasing the reading till 255°C and then it pass again at 0.
I am not sure if I have a problem of range or if the bits above 14 are stuck at 0.
I also watched T∆ and it seems like it is also between 0 and 255°C

Grove - I2C Thermocouple Amplifier MCP9600 can’t work alone; it must work with a k-type thermocouple.
May I ask if you have used the Thermocouple Temperature Sensor K Type-1M sold in our bazaar together?
this k-type thermocouple on our website has a measurement range of -50℃ to +600℃.

I used a k thermocouple not from your store, I have several in stock and the temperature reading is good.
The problem is that it is modulo 255.
I verified my measurement and they are good. and even above 255°C the reading value modulo 255 seems correct.
I just don’t know how to have the full scale value from my reading of TH, pointers 0000 0000.