First question

[sussamb]

You can't report it via Express can you? Either directly to HERE, Garmin's map provider, or to Garmin https://my.garmin.com/mapErrors/report.faces

Sounds like it could be incorrectly set as one way. Did have an instance where that was the case a year or so away, now been corrected.

[EZMotoTim]

Putting the same waypoints into Basecamp results in a load of doubling back and a total trip of 449km

I realize you posted this last year, but this might be of help. Either Tyre or Basecamp has rearranged the order of the waypoints. I see in the Basecamp png that you have the waypoint list open. Reorder the waypoints using the up and down arrows to put them in the proper sequence. The routes should be quite similar when the order is right.

The next step would be to make sure the points are all on the roads and in the proper lanes. Be sure "Cneter map" is checked then click on each point in the list and move any points that are not where you want them.

Tyre and Basecamp do not use the same maps, so its possible for the points to not land in the same place. I've used Tyre for many years and have had no problem transferring the routes to the Zumo 665. I've not tried bringing routes into BC. It's probably best to work in just one product.