How does Auto Sync work?

Auto Sync works only after you turn it on in Settings and complete the normal Fitbit and Apple Health setup in the app.

SyncFlow does not choose an exact schedule. iOS decides when background work is allowed, so Auto Sync may run multiple times in a day, later than expected, or not at all for a while.

Background runs are intentionally limited to recent data only. SyncFlow checks a small recent window instead of doing a full-history sync in the background.

If iOS restricts background tasks or Fitbit needs you to sign in again, Auto Sync waits until those conditions are cleared.

SyncFlow also skips overlapping runs so manual sync and Auto Sync do not write at the same time. If you force quit the app, background tasks may stop until you open the app again.