Sync looks out of date

When sync runs

On launch, when you switch profiles, and in the background while the app is open. A TV that has been asleep for a week syncs when you next open it, not before.

The usual causes

The other device has not been opened. Nothing has been missed; it simply has not looked yet.

The same profile is open on two devices at once. Both are writing progress for the same profile and the later write wins, which can look like changes being undone. Use a profile each.

Different accounts. A device signed in with a second email address is on a second, empty account. Check the email shown in Settings → AnyTV account on both. This is the single most common explanation for "my library did not sync".

The device is not connected to the account. It may hold your library without being on your plan, the Devices tab lists these separately under other devices with your library. Connect it.

Forcing it

Open Settings → AnyTV account and sign out and back in on the lagging device, then reload content. Nothing is lost by doing this: your library lives on the account.

Downloads

Downloaded files never sync. Only the list of them does. See What syncs, and what does not.