Please help I ran a half marathon this morning and my Garmin Forerunner 35 has only uploaded half of the run. It initially wouldn’t sync nor come up on Garmin Connect! We have managed to import the file but only half has come through. Please help!

Please help I ran a half marathon this morning and my Garmin Forerunner 35 has only uploaded half of the run. It initially wouldn’t sync nor come up on Garmin Connect!  We have managed to import the file but only half has come through.  Please help!