Okay, for those like me, loading the 3mf file and having a sliced version not showing the temperature change, here are the steps to do it :
1) Click on slice
2) Go to Preview
3) Using the slider on the right, move down the upper one to the first layer at 215°, then right click on the plus button, choose "Add G-Code" and add this : M109 S215
Do that again on each starting zone when the temperature change, and change the "S215" part to the desired temperature in celcius.