I've been using the treadmill quite often at the moment since the weather outside isn't exactly ideal running weather, but as a user of Strava I find it quite infuriating.
When I save and calibrate the treadmill run on the 935, the calibrated workout is uploaded to Garmin Connect fine, but the original workout is uploaded to Strava.
I then have to delete the activity on Strava with the inaccurate distance/pace data and add a manual activity with the correct data. But I lose the heart rate data from the original activity and there is no way of adding this data to a manual activity.
I hope Garmin is reading this and will address this problem in a future update.