I had started to play this mission yesterday. After playing a few miles, i saved the game and left Today i started from where i saved the game and everything was fine for first 5 mins. Then the weather changed to foggy conditions and snow dissappeared completely. Surface and trees looked like spring. At first, i thought that it is due to the scenario and it has dynamic weather. I liked it in fact. Then again i saved and left. After i re loaded the game, everywhere was snowy again! After another 5 mins, spring came again, i saved to check what is wrong, and loaded the game, snow came... What is wrong here? Save game feature? This particular scenario? Snowy weather?
Don't use save feature if you don't want weird problems, it is still borked. Weather, mission objectives, loco controls, safety systems, signaling... Any of these can and will go awry after reloading a save quite probably.
