First, check that your Apple Watch is connected to your iPhone via Bluetooth and both devices have Wi‑Fi or mobile data turned on. If that looks fine, restart both your iPhone and Apple Watch and open Hiiro again to trigger a fresh sync.
If workouts still don’t appear, make sure Hiiro has permission to write workouts in the Apple Health app, then try logging out and back into Hiiro or reinstalling the watch app. If nothing works, contact Hiiro support from within the app so the team can investigate your specific setup.