Garmin Connect Courses elevation gain grossly overestimated.

When creating a course on Garmin Connect the elevation gain is grossly overestimated. I can download the GPX and upload to other programs (e.g. strava) and the courses match reality. It is very large over estimate of 30-40% and obviously wrong by inspecting the plot. Anyone else seen this and is there a fix?

Note same file in Strava is approx 3200m elevation gain.