This suddenly happened to me when playing on Tehachapi Pass. Then I decided to restart the scenario and then it came back to normal. Has this happen to anyone else then the wagons suddenly decided to tilt like this?
Think that's been a thing forever, mostly on US freight because of the sheer length of trains, but like you discovered a restart of the scenario usually cures it. As for the cause I'm sure more knowledgeable people than me could better explain it and say whether there's a fix for it or not.
