In Belgium the winter, you might well have temperatures below 0 C. However, in the summer, you should be well above freezing. A temperature of minus 44 C is the kind of temperature that might be experienced in winter near the Arctic Circle, not in Belgium.
Since you replaced the thermocouple, the problem likely lies elsewhere such as the controller. It might be that the problem can be corrected by reloading the firmware. Hopefully, the Traeger is still within the warranty period. AFAIK, there are no Traeger employees who monitor this forum. We are Traeger owners like yourself. Contact Traeger customer service and send them your video. If reloading the firmware does not fix the issue, they might send you a a replacement controller.