By default, the Apple Watch requires that you manually reopen apps after reactivating the screen. This is something that is controlled by Apple Watch settings and not Golfshot itself. Update your settings to have the watch automatically open Golfshot while in play.
Watch settings: Settings > General > Background App Refresh - make sure it’s on for Golfshot
Watch settings: Settings > General > Wake Screen -
*Turn all settings ON in the first section.
*In the “ON TAP” section, set to “Wake for 70 Seconds”.
*In the “ON SCREEN RAISE SHOW LAST APP” section, select “Within 1 Hour of Last Use”.
*In the “RETURN TO LAST SESSION APP” section, Turn Golfshot ON.