Updated course sync's old route to Edge

I've just been having an issue I discovered last night while navigating a course. To summarise, an updated course will sync the original route to the Edge or, more precisely, GC generates FIT files with the old route data. The only solutions I have found are:

• duplicate the course in GC and sync that.
  
• export a GPX file and place it in the Edge's /Garmin/NewFiles folder.
  

I've sent the following to Garmin support:

I created a course in GC and sync'd it to my Edge 820. Later I changed the course route and re-sync'd it. When reloaded the 820 still had the original route but said the distance had changed.

Checking GC and the course shows the updated route. Multiple attempts to get the new route failed (deleting FIT file on Edge; iPhone GC sync; renaming the course; sync via website/GEx).

I downloaded the course from GC as FIT and GPX files placed in NewFiles (separate tests) and restarted. The GPX has the new route but the FIT still has the old route.

I changed the course route again and re-downloaded new FIT and GPX files. Again the same result: GPX is updated and FIT has the original route.

In both files the 820 displays the summary information correctly, e.g. the distance is right.

It would appear that GC is not updating it's cached course data for creating FIT files.

If I duplicate the changed course in GC, save and sync it then now the updated route is sent to the Edge.