Your runs and Apple Health
My Garmin run is not showing up
A run recorded on a Garmin watch reaches Why Not through Apple Health. Garmin Connect writes the run to Apple Health when it syncs, and often that happens only when you open Garmin Connect on your phone.
Open Garmin Connect, let it finish syncing, then open Why Not again. The run usually appears within a minute. The same goes for COROS and Polar watches.
If a run still has not arrived after that, check that Why Not can read workouts from Apple Health.
iPhone Settings, Privacy & Security, Health, Why Not: turn on Workouts and Workout Routes.