I completed a treadmill run for a suggested workout, and added the distance at the end as part of the treadmill calibration step. I inadvertently put in the wrong distance as I thought the treadmill used miles, which I converted to km and entered to watch. I realised my error when my performance stats suddenly took a jump (never use a treadmill normally) so I corrected the distance in the Garmin Connect iOS mobile app by editing the activity.
This doesn’t seem to sync back to the watch though, which is still showing the incorrect distance, and my performance stats on both seems to have taken an incorrect jump and don’t seem to have been corrected by my edit (that is: the race predictor times have improved, VO2 max never moved as per usual!). Is this a bug/known behaviour?