Flame Boss Meat Probe

I discussed this with the owner of FB a while back. When it was designed it was speced out that the lowest it would read is the ambient temp of the control unit.  There is a reference thermocouple internal to the head unit.  Since it is a cooking only controller, there is no real need of showing temps lower than that. As soon as the meat gets warmer than the surrounding air temp, the display will start to climb. In some industrial temperature controllers that will never be used for cooling operations this is a design parameter that can be selected.  It allows for better accuracy as calibration does not have as wide a span as a unit that has to go from say -40°F to 500°F.  You can have it go from ambient to the thermocouple high limit (typical type K are 2500°F). Even in the case of sous vide the controller would function properly as it is a heating application although a relatively low temp.
I accidentally discovered this same thing when I was working on a defective refrigerator and thought I would just pop the probe into the freezer to check its' temperature.