@Grahame-Lancaster Tip: You should check each route point after expanding a route. Zoom in all route points completely and make sure they are placed correctly. Move route points if they are too close to: roundabouts, road intersections, exit roads, roads with separated lanes, wrong side of the road or viaducts.
Here is RP19 from your route, one that has been added by the system. When possible, you should try to consider a 20m ring of uncertainty for each route point. This is to allow for errors in the mapping and a weak satellite signal while navigating. RP19 could be seen by the navigation device as being on a number of roads here.