The issue is more likely the length and/or complexity of the route. Also note a route on your device can only have 30 waypoints.
Well nothing else is likely to be the issue, since splitting it seems to work for you.
I guess. Maybe something strange about that particular route. I'm away at the moment so unable to check it out for you.
I would appreciate that. I modified the route by taking it down to 6 waypoints not including the start and stop and still the same issue. Won't save to the zumo. By chance do you know how many waypoints are allowed? I can send you the route if that helps. Thanks.