I have noticed that if I create a new segment Garmin connect only reports my results from the date it was created onwards it doesnt look backwards to check my previous efforts within historical rides.
Strava has optionality to request a refresh I think Garmin should also offer this.
People now have lots of history and if you create a new segment you dont only want it to be active then you would want to see against all of your efforts whenever they occurred.
Please add this function Garmin!