Garmin Instinct 2X gives the wrong latitude and longitude

I fixed GPS position after turn the watch on ,it gave me the first latitude and longitude. After that,I enter the navigation menu and quit. Then I fixed GPS position for the second time，it gave me the second latitude and longitude. I checked the two results in Basecamp,the first one is correct,the second one is wrong,it is 626 metres far from the first one. If this happen in the wild could be take people into danger Is there somebody know how to fix this?I need your help !Thank you!