Name the missing state precisely
A film marked watched on one server but not another is a different question from a film resuming at minute zero instead of minute thirty. Plex’s account-level watch-state feature does not treat those observations as the same data. Before changing a server library, record whether the missing result is a watched flag, a personal rating or an unfinished playback position.
Read the supported sync boundary
Plex says in-progress information is not synced by this feature; completed watched state is. It documents account opt-in, a sufficiently recent server and supported metadata agents for personal libraries. A change can also take time to reach another personal server. Signing into the same account therefore does not establish that an unfinished position should follow through the global watched-state mechanism.
Compare the intended cross-server task
For example, someone pauses a legally held film on their own server and later opens the corresponding title on another authorised server. The absence of the paused position does not, on its own, prove that the watched-state preference is broken. Keep the title identity and selected edition clear, since a different cut can have a different timeline. If the actual issue is a completed flag failing to sync, inspect the documented account and metadata prerequisites instead. Avoid manually marking an unfinished film watched merely to test a resume feature that the sync does not supply. Report the particular state and server context without exposing library access tokens.
Questions, answered
Will this feature move a half-watched position between personal servers?
Plex explicitly says in-progress information is not synced by this watched-state feature.