I have just bought Southeastern highspeed, and downloaded Northern Transpennine from the Preserved Collection. For both of these the trains I would expect to see are not available in Timetable Mode. In Southeastern highspeed the only options available are locos from other routes to run the railtour specials: Class 47/4, Class 45/1, Class 37/5 and Class 40. The training modules and scenarios are available for Class 375 and Class 395, but they aren't available for running in timetable mode. In Northern Transpennine all the expected loco options are available (Class 47/4, Class 45/1, Class 08, Class 40), but the DMU option (Class 101) is not available. I also have the BR Heavy Freight Pack and Tees Valley Line installed, as well as others that don't appear relevant. Has anyone else seen this, and are there fixes I can try? Is it worth uninstalling and reinstalling any of these routes?
Try verifying files. Have you moved the installation to a different drive? Sometimes that can mess things up.
If you don't have any luck after reinstalling then I would suggest submitting a ticket to DTG You can do this by clicking support at top right of this page