I wanted to do a scenario with the 1938 Stock from Elephant & Castle to Queens Park, and when I went to use the Master Key, nothing happens as you can see in the video. I have used this train many times, and I know how to set it up, but I do not know why this has happened.
I did it again on foot as opposed to a scenario and it worked just as it should. But I will look at the scenario again soon and see why it might not have worked properly.