Looking into that, I connect the Montana to Basecamp on the computer, find the two kinds of routes on the Montana and export each to a text file. Looking at those files, there is a difference. Both have a list of waypoints defining the route. The route imported from basecamp also includes all of the routing points generated by the Basecamp routing software and map to travel between the waypoints. The route has been pre-calculated and included in the file. The hand loaded route has no routing points. The routing will be calculated by the routing software and map in the Montana, and may differ from the Basecamp routing.
Apparently the Montana doesn’t want me to modify the imported route waypoints and recalculate, or simply recalculate, because the unchanged portions of the new route could be different from the route planned and calculated by Basecamp.
In my use the route has 25 waypoints selected from 50 possible, to be visited in 12 hours with waypoints added or deleted during that time. All waypoints are entered into Basecamp and a route is developed using 25. I can export the 50 waypoints to the Montana and would like to export the route waypoints without the detailed routing information so it can be edited and routed on the Montana. Failing that I would like to find a GPS unit that allows editing and recalculation with imported routes.