Major Ascent Issues

What do the elevation plots look like for GC and Strava? Do they look believable or are there artefacts?

does this help?

Apart from scaling issues they look pretty similar - Does Strava and Garmin agree on start time/end time of activity as well? I know strava do some smoothing but it's not nearly so severe as to take a mile off

Next run, manually calibrate the altimeter and see if they agree

I've just checked a run similar to yours in elevation and distance





Ignore the time discrepancy - Strava shows moving time and GC shows total time (I take a lot of photos lol) and they roughly agree - so yeah, try manually calibrating the altimeter before the next one

I did both altimeter and barometer right before run

On GC you can disable elevation corrections for an activity (on the web page)





Do the two agree if you enable elev corrections? Do you have 3d speed and distance on?

IF they do, the altimeter is probably to blame - both Strava and GC's correction if i recall correctly lock the activity to the DEM elevation at each position.