Hey @mhoos,
Thanks for the follow up. Some activities will have only one distance stream available. When a device does not write a distance stream into the file whatsoever, we would use the GPS data to calculate the distance by adding up the distance from GPS point to GPS point. We may do some smoothing to remove outlier GPS points - this includes inaccurate GPS points and data that is clearly inconsistent with the file. We are unable to manually adjust the distance recorded in this upload at this time.
One thing to check for future activities is to ensure you are uploading the original .fit file from your device, ensuring your have a strong GPS signal prior to starting your recording, and keeping your device up to date with the latest firmware.
For more information, see our article on How distance is calculated for your activity. If you would like our team to take a look at a specific activity to see if this is available, please submit a support ticket and include the activity link and they can take a closer look for you.