The problem is that Wallingford is the first (1) and the last stop (3), which is not necessary and can in fact cause problems (the train tries to go from (3) to (1), which it can´t because it is the same stop and will eventually give up and skip it).
The line will be fine with 2 stops, so just delete stop (3) and everything should work including the overlay and frequency. People will also start using the line when it gets valid.
Best regards,
Tom
