I can add some info to this now which may help in identifying the cause of the problem with IGO Primo software.
I created a route on a site similar to Plotaroute (Motogoloco.com) and exported out to a KML file, which I then uploaded in a similar manner to the Plotaroute version, and it works perfectly.
Now I accept that perhaps I am doing something wrong in creating these routes in Plotaroute, and I hope that is the case, because Plotaroute is easily the better tool for this work, but at present it repeatedly confuses the hell out of IGO Primo so that it jumbles the order of the waypoints, really crazy stuff. The structure of the KML file from Plotaroute is completely different to that of either Motogoloco or Tyre, another route creator, which may mean nothing, but importantly, IGO can read both of them and not Plotaroute's KML.
I hope someone from Plotaroute reads this and can offer some suggestions as to the cause.
I have been creating routes using plotaroute.com which exports to a .KML file, and I have no trouble with this process, and IGO Primo will load it and read it.But that's about as far as I usefully get. I created a route that starts from home and ends about 50km away, after completing a loop to the north and back to that point 50km away. Whilst I can see it in Primo, with all its little yellow flags delineating the route, when I actually ride it, it seems to ignore those waypoints in favour of the shortest path to the destination.You can see this route here:- https://www.plotaroute.com/route/335612This is particularly problematic if its a return loop because as soon as I get to the first waypoint it directs me back home!
So the question is whether anyone has managed to load a route into Igo Primo, and probably the same in Igo8.