Misreading Standing versus Seated position

New customer of Vector pedals.  

I went for a ride and Garmin Connect reported I stood for 15 minutes of the 60 min. ride.  But this is wrong:  I didn’t stand at all.

Any idea why it might be misreading my standing / seated position?

I found a similar thread about indoor here, but my ride was outdoors.

https://forums.garmin.com/sports-fitness/cycling/f/vector-3/141832/cycling-dynamics-total-standing-in-indoor-trainer/789403#789403