Won't route on cycle route

First of all, thanks so much for creating this wonderful site, it's a real treasure trove. 

I was tinkering with the coast and castles route and found that it wouldn't route over a bit of the cycle route (ncn1, ev12). Must be something to do with how it's labelled in the data. The location is just east of Cheswick where it crosses the railway line. Neither the bridge nor the gravel track on either side will accept a route.