A popular Firefox browser add-on that saves and syncs bookmarks has started to lose those bookmarks instead, users are complaining. From a report: According to user reports -- and your reporter's own experience -- the problems arose when Xmarks updated the add-on to version 220.127.116.11, the first version to work on the new WebExtensions API, Firefox's new add-on technology. Since then, Firefox users have reported a wide range of problems, but among which the biggest was the fact that Xmarks was not syncing bookmarks as it should. The problems did not manifest the same way for all users. Some users said the add-on stopped syncing new bookmarks altogether, some reported corrupted links, others said they lost all bookmarks, while other reported that only a small portion of new bookmark URLs was being added to their Xmarks account.