I've routed using Graphopper on both the A17 and the road past Old River Farm with no issues.

One thing that has come up in the past is that some routers will not route past a flooding point: there seems to be some dataset somewhere that lists the places where the road closes in flood conditions, and treats them as permanent blocks.

Your pin is quite close to a bridge over the West Lynn Drain, and that is a likely flooding point in this very flat part of the country. Might be something to do with that?