HERE Routing API not returning correct truck routes, even though correct routes are available

Question

When using the HERE Maps router API to calculate a trucking route in an online application, we encountered an issue where an invalid trucking route was returned even though a valid trucking route existed.

We believe this to potentially be a bug in the HERE platform, as our request is well-formed, and reversing the origin and destination does return the correct route. We are of course open to any corrections we can make on our end.

Here is our request body:

{
  routingMode: "fast",
  transportMode: "truck",
  origin: "42.946054623602855,-87.91001428574813",
  destination: "42.870838078655176,-87.88293617736036",
  return: "polyline",
  units: "imperial",
  spans: "truckAttributes"
}

We are using the the endpoint documented here: https://developer.here.com/documentation/routing-api/api-reference-swagger.html

A map of Oak Creek, Wisconsin. Two routes are shown - an incorrect one in dark blue, and a corrected version in pink.

Here is a screenshot directly from the relevant app, with potentially identifying information redacted and a corrected route marked. The pink line is a representation of the correct/expected route, and the dark blue line is the polyline that the system actually returned. The pictured point is the destination, and the origin point is off-screen.

It should be noted that when reversing the destination and origin, the correct route is actually returned (this screenshot was generated usingan official reference tool):

A map of the Milwaukee area, including Oak Creek, Franklin, and Greenfield. A correct trucking route between two points is displayed.

However, due to the nature of our application, it is very important to keep the origin and destination as-is within the logic of the code, so swapping the parameters isn't actually a solution to our problem.

Changing the waypoints in any way is also not a feasible solution - the waypoints in our system are provided by the user, and users will often have specific reason to place waypoints in very specific locations.