I am sorry you are having GPS distance issues with your Fenix 5X. Unless there has been a hardware failure, you may be able to resolve the issue by resetting your watch. There are two different resets you can try:
1) Hold down your top left power button until your watch shuts off, then let go of the button and test your distance functionality
If you are not able to resolve the issue with either reset, please use the contact information on the bottom of the Support Center article to speak with your region's Garmin Outdoor Wearables Product Support.
