Why does Fitbit data look duplicated or missing?

Fitbit's API only syncs data recorded by Fitbit's own devices, so third-party data routed into the Fitbit app will not arrive.

Fitbit's API only syncs data recorded by Fitbit's own devices, so third-party data routed into the Fitbit app will not arrive. Empty body/measurement arrays usually mean the provider has no compatible source (for example a connected scale) actually writing those metrics, not a configuration problem.

Separately, each Fitbit payload being a complete snapshot of the current day so far is expected behaviour, not duplication. Fitbit notifies throughout the day, and Terra forwards the full current day each time.