ios10.3 backgroundLocation

we have one APP running in background which will upload the location information with a five minute interval ,we find it works before iOS 9.0 , but it fails after iOS 10.3.1 , our APP won't upload the location information every 5 minutes in iOS 10.3.2 after the screen light turn off , in most worst case there is only one location information uploading for 1-2 hours , it's really weird ,we wonder if there is any difference for iOS 10.3.1 compare to iOS 9.0 about the app running periodically in backgroud when the screen turn off. any suggestion or idea ?

thanks in advance