If you forget to reconnect, launch the game again while online. Ubisoft Connect usually reconciles the local save file.
The phrase refers to the automated background processes used by Ubisoft Connect (formerly Uplay) to manage your gaming milestones and software updates. uplay ach earn achievement download upd
No. Achievements are tied to your Ubisoft account, not local files. They will reappear once you sync. If you forget to reconnect, launch the game