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Forerunner 10/15: Elevation Data is Missing in Garmin Connect
The Forerunner 10 and 15 do not show or record elevation information when recording an activity. Each watch will record the GPS data (latitude/longitude) in the activity track. When the saved activity is uploaded, Garmin Connect will use a digital elevation model to create an elevation profile for the saved activity. If an elevation profile is not created, you will need to delete the activity from Garmin Connect and import the activity again from the watch.
Deleting Activities from Garmin Connect
Sign into Garmin Connect from a personal computer
Select Activities from the navigation bar on the left
Select All Activities
Locate the Activity you want to delete and click on the trashcan icon to the right of the activity name
Select Delete to confirm
You may need to refresh the page to show it has successfully deleted
Manually Upload Activity to Garmin Connect
To manually upload the activity back to Garmin Connect see: How Do I Manually Upload an Activity I Recorded to Garmin Connect?
Once complete the elevation graph should now show properly in the Activity's page.