I am using supporting points in the RESTful Calculate Route API (https://api.tomtom.com/routing/1/calculateRoute/54.57108,-1.201036:54.57108,-1.201036/json?instructionsType=text&traffic=false) and generally it is fine. It recreates my route from the points I have given it but occasionally it routes me off the supported route for a while and then back onto it some time later and cannot work out why it does it.
The image shows my supporting route points as a polyline that is red and green going along the road to the roundabout and all the way around the roundabout back onto the other side of the road. The returned TomTom route based on the same supporting points used to create the red and green polyline is shown in black.
As you can see it leaves the route at the junction before and goes a strange non direct route back to the next roundabout. I have set traffic to false in the request.
Any ideas what I am doing wrong or suggestions of things I can try?