80 says MRA (it’s the ACT UK Day1 track).How many waypoints?
Once in Tread, there’s an option to “Convert to Route” which I think I used. You’ll need to check that it’s not rerouted anything though.
Garmin is fairly specific on the differences between tracks and routes.
Differences Between Routes and Tracks on a Garmin Automotive Device | Garmin Customer Support
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