the garmin could be taking a slightly different route
make sure you zoom in to all shaping points on basecamp and make sure they are on a road and not just off it otherwise the garmin will try taking you off the road!
Imported route split?
Re: Imported route split?
Look carefully at the routes, what I do is compare them both in BaseCamp. If you change the colour of one you'll see more easily if there are any discrepancies