1) When you play the "Open All Hours" scenario, the weather is raining. If you switch cabs, only one of the cab's has the windshield wipers clearing the raindrops off the windshield.. So on your return trip, it is impossible to see the signal colors. 2) Furthermore, I tried to drive from the outside view,,,although there is the indication to press Sifa button, you don't see a signal that would make you press the acknowledge buttons and the the emergency brakes get applied. Don't know if this is also a bug, or if I am missing notices by not being in the cab. 3) From the outside view, if you want to go back into the cab, it puts you in the cab that is facing the coupled cab so you cannot see where you are going (and since it is not the active cab, you cannot get instrument information). You can only switch to the correct cab by stopping,,,but then you are back with the windshield wiper issue.
Have you reported the problem? https://forums.dovetailgames.com/threads/reporting-a-technical-issue.31193/