I'm unable to enter timetable mode with the Cathcart Circle DLC, as the game thinks there is no locomotive to choose to see the timetable. Unlike other routes where you can choose the weather and pick one of the route's trains, the Class 314 isn't there to be chosen. I've tried verifying the files in the Xbox app, and it's reinstalled the game, but nothing changes.
Fixed it by downloading a Class 314 livery from the Creators Club in game, after that the new custom livery and the original showed up fine. Weird.