Interesting thanks for the report. I have never thought about this to be honest. Isn’t there a way to change the sorting approach in basecamp?
There is nothing wrong with using basecamp and the resulting route will be probably better than using the other options, but there are alternatives so you don’t have to use basecamp, for example the GarminShapingPointGPX or to export the track and let your Zumo calculate a route from the track. For example see this topic: Export Garmin compatible GPX
Let’s see if others have the same issue 
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