Maybe I'm missing something somewhere but, I'm trying to create a scenario with a HST from London to Reading on the London to Brighton line and it's not listed in the available trains. Claims I have 30 trains to choose from and the dmu from London to Reading does show up in the trains I can choose from. Also noticed that it will let me tick the box for "off the rails" but, won't let me confirm it. I'm playing on a PS4. From what I can work out from what I remember of class numbers, it looks like it's just UK trains.
Just checked on PC and I needed to put off the rails mode on. Then it shows as "High Speed Train GWG" and gives me various consist options
If you can't go into off the rails in "Set Scenario Details" then I would send in a ticket as there would be a much bigger problem with the scenario editor on your machine
