NAVIGATION SYSTEMS GREATER THAN 6 WAYPOINTS SOLVED!
Ladies & Gentleman, I found a solution that is working for me to import complex routes into the Yamaha Navigation system on our bikes. It isn't perfect but it works for me. You will need to use/ any software that exports a GPX file in a "Harley Davidson Boom Box Pre 2019" format or purchase a mapping package called MyRoute-app. It is made by the same people who make TyreToTravel which I have been using for many years. The GPS system is made by the same company that makes the GPS system (Boom Box) for HD from my understanding. So MyRoute-app has directions on exporting routes into the Boom Box. I am using 2 routes that I created that are both about 500 miles and have between 40 and 52 waypoints on each file. The entire route will load into our GPS systems, depending on how far apart the waypoints are, and the number of roads in between will determine if the algorithm changes the route slightly. Regardless, all we need to do is to export the GPX file as a "Harley Davidson Boom Box pre 2019" option. The GPS will load the entire file and read. Import as a track and it will allow you to hit go and it seems to work.
I don't know of anything else that works, but I'm sure there are other products. I am using what I have available to me and just publishing to you my findings.