If you do not have the wearable app open, it is not syncing between Garmin/Fitbit account and InsideTracker app. Best practice for wearable accounts and devices is to keep them open in the background on your iPhone.
Some other Troubleshooting tips:
- Log out InsideTracker app, swipe up/close app on iPhone
- Log back in
- Next step if not working-
- Disconnect device from the InsideTracker account page
- Reconnect device and then log back into the app, check account page to confirm connection