@B Gregory wrote:
….. the Zumo 550 won’t accept or allow loading tracks from an external source. It can make it’s own internal tracks that you can export but you can’t import tracks into the Z-550 and have the Z-550 use those tracks to route to or even show them as a visible track on the screen.
I do this all the time. Save the tracks in a GPX or GDB file and upload it to the Z-550. Turn recalculation off on the 550 and then go to import “tracks”. It will turn them into routes.