This is happening the second time now:
I start a heaven evacuation mission and one of my soldiers starts on a tile where there is a fire, thus the soldier is on fire.
Starting on fire
Re: Starting on fire
This is a vanilla bug sadly. Its probably the same bug that lights advent on fire and activates a pod halfway across the map. Do you have the Dev console turned on? If so just ttc him to the tile next to the fire.