Im having similar issue. When I had this missing uderscore… thing, I tried to reinstall the game and yeah it worked, I finished my PPL exam and I was looking forward to do my first mission. But now, it keeps loading me in that PPL exam again and again. Even if I try to do freeflight, it loads me in exam. Guess I will have to reinstall the game after every mission or freeflight, because only thing I can do now is tutorial and activities.