Time issues after pausing activity in Strava Flybys/Group Rides

If I pause an activity (stop button) and switch off my Edge 840 the time seems to be wrong afterwards. Example: Activity paused and garmin switched off for 30mins but the actvitiy timing shows a break for 4 mins. On Strava this leads to wrong flybys and missing group rides since every other rider paused for the full 30min and I'm 'ahead' of them.