I am not Garmin, but I also do not think you need anyone from Garmin for that. It is not difficult at all and there is no bugging as far as I know.
You just drop the file on the right page, do one click, and it is done. You just have to do it on the right page. If you try importing an Activity in GPX format you do it on the page Import Data and if you want to import a Course, then you drop it to the Import function accessible on the Courses page (note the Import link at the bottom of the white window). It is as simple as that. I do not think it could be done much simpler.
Thank you Trux for taking as the stupid one, understanding nothing. Big firms usually die while they ignore signals coming from the base consumer. Off course I go to garmin Connect, import activity. So here is my suggestion : trace your own circuit on "ridewithgps", export from ridewithgps as a "gpx" or "fit" file and the import on garmin connect, by clicking on the righ place.
I have no idea what ridewithgps is, and do not intend searching it, but if their files do not import into Garmin Connect, then they apparenlty are not quite compatible wth the Activity file format, and you should be perhaps complaining on their side.
Anyway, you can try passing the FIT file through the Section Remover at Fit File Tools (without removing anything) and see whether it fixes the incompatibility, and can be then imported. If it does not help, post a sample GPX file here, so that I could check out where the incompatibility is.
