SD75 dynamic brake issue.

I just tried the scenario "Held up by the highwaymen" and the train spontaneously derails going down the grade toward San Bernardino. I have FanRailer's SD75 physics mod, but that doesn't help.
https://www.railworksamerica.com/forum/
https://www.railworksamerica.com/forum/viewtopic.php?f=29&t=18973