Welcome to the Traeger world. The probes are notorously inaccurate. Yes, you can calibrate them using an ice/water bath at 32 F/0C, but that data point is useless for cooking. What you really need is a probe that is accurate between 120-205F.
I used the internal meat probe on my Ironwood a couple of times, but have not plugged it in since. You can use it to monitor the cook, but get yourself a good instant read meat thermometer for monitoring the final temperature of your cook.
The most highly recommended meat thermometer is the ThermoWorks ThermaPen. It is widely used by professional chefs in restaurants. However, it sells for $109. If that is a little steep for your budget, there are other brands such as ThermoPro that are quite serviceable, but cost less and might not be appropriate for daily use in a professional kitchen. An instant read thermometer would make a great stocking stuffer for Christmas.
Two things to look for are accuracy of +/- 1 degree F and a read time of less than 3 seconds. If you get a probe that takes 10 seconds to read, you will get frustrated trying to probe multiple pieces of protein.
You can also get remote temperature probes that will allow you to monitor you cook from your cell phone.
