As mentioned, that setting can take time to update so it may have still been enabled. If you try a clean install now, it should not sync the old played status.
I reenabled the setting right after my Ubuntu install.
Why did you re-enable the setting? I thought you didn’t want things synced up with plex.tv?
I just want a clean slate
We do not currently have a way to remove the synced status from plex.tv. If you disable the feature and wait long enough before a clean install, it won’t re-use the info. But if you re-enable that setting, it will come back.