I see numerous threads about elevation discrepancy between devices, but I am curious about massive discrepancies (100%) between the same file uploaded to garmin training center vs garmin connect. Some of the other data is different (upload of only one lap includes all laps as an example), but the elevation is way off.
The difference between GTC and GC is most likely because you have elevation correction enabled on the latter. If you turn that off, the numbers should be the same, more or less. As the other threads on these forums have pointed out, Forerunners try to get elevation from GPS, which doesn't always provide good accuracy.
Without more details, I'm not sure what is going on with the other discrepancies. I'm afraid I don't understand what you mean by "upload of only one lap includes all laps as an example."
