Fix that worked for me – Garmin Connect 5.21 / iPhone
After updating the Garmin Connect app, my watch (Forerunner) stopped syncing. Bluetooth showed the watch as connected, but the app couldn’t find it.
I tried removing the watch from Bluetooth and re-pairing multiple times without success. What finally worked:
1. Updated the watch firmware
2. Synced the watch via WiFi
3. Uninstalled the Garmin Connect app
4. Fully powered off the iPhone (not just a restart)
5. Turned the iPhone back on
6. Reinstalled Garmin Connect and re-paired the watch
The key step for me was fully powering off the phone after uninstalling the app – not just restarting it. Hope this helps someone!