Your data (temporarily) disappears because of something posted by a completely unrelated user.
Syndicated copies to:
Tuesday at about 4:50pm Pacific time our web application at app.simplenote.com went down, displaying a generic 404 error message. We discovered shortly after that Google Cloud Platform, which hosts the web application, had shut down the site due to a DMCA notice for allegedly infringing content that...
A bit crazy for a major web app to go down for a silly reason like this.