I have had no end of problems syncing courses from Garmin Connect to my devices. I attributed some of this to the oldness of my FR305 and then the general lousiness of the Fenix 2, but there, I could use Basecamp as a workaround. I replaced the Fenix2 with a 310xt today, and I love how that device operates, but I could not get courses to sync to it. (Syncing of other stuff, like workouts, was doing fine, so I knew setup wasn't the issue.)
After a little testing, I figured out it was more specific: I could not get courses created from activities in Garmin connect to sync with any of the devices, the 310xt in particular being the sticking point, since it's my new go-to. While explaining this to a tech and pulling out my remaining hair, I quick drew a course around the block and that synced just fine. While I was on the line with the tech, by the way, he tried making a course from an activity then syncing it to his Edge. Same problem with sync error. He was unamused. It appeared that courses created from activity were corrupt and incapable of syncing, while those drawn from zero were just fine. Crazy, but that's what was happening.
It wasn't until after my run that I wondered if I couldn't make a course created from an activity into a course that behaved like one drawn by hand: just open up a course created from an activity, perform some kind of minor edit, and get it to behave as well as a course drawn from scratch. (It's a big time saver to use the activity, and in the case of some trail races -- where I most need a course to keep from getting lost -- drawing it on a map might be impossible.)
So, I opened up one of those courses in Garmin connect that would not sync -- a course created from an activity. I edited it, moved a few waypoints, zeroed out the time, speed, etc. I saved it. I sent it to the 310xt. It synced just fine.
I tested it again just opening up another unsync-able course from an activity, but this time just zeroed out the time/speed, etc. I left the points alone. Saved it under the same name. That one synced just fine as well. This was a 101km race in mountains. It was huge. It worked fine, even draws a beautiful (and horrifying) profile.
So, if you're having trouble getting courses to sync from connect, try the following:
View it in full detail
Hit the edit button
zero out the time/speed, etc.
save it
send it
I hope it works for you too.
