Hi, During the tutorial for the Class166 (GWE) you need to set the head lights to day. For some reason, this setting is not available, not using the keyboard and not using the control in the cab. It is not related to the tutorial, it is a bug in the train itself. EDIT I tried the tutorial again. It is working if you directly use the headlight switch, but it is not working for the keyboard. Somebody forgot to implement the this setting in the keyboard mapping.
You can set the headlights in the cab, at least on PS4. All tutorials on GWE completed successfully at my end.
Once you have turned on the lights or made other settings in the tutorial, they are often locked. However, this is the case in many tutorials and has no effect on the trains in scenarios, journey or timetable mode. I have driven a lot with the "new" Class 166 and it works perfectly. And even Shift+H turns the lights on, just hold it a bit. There is one exception, sometimes you have to open the opposite doors to let passengers in or out.