The simulation server is currently experiencing an issue that breaks the save upload process. Do not try to upload saves, it won't work. The client will tell you that your save was successfully uploaded, but when you try to open the save from the browser, you get a 404, and the thumbnail says "save file invalid". There is currently nobody online who can fix this, nor anyone who can disable uploads to make the problem more obvious. Sorry for the inconvenience. I'll edit this post when the issue is resolved.
I have restored around a dozen saves that were corrupted during this, using the most recently saved history item. To view your save's history, copy the save ID and type history:mysaveID in the search bar. All published saves that had history were restored. I didn't go through the unpublished ones yet. Any restored saves won't have thumbnails. Open them and resave them to restore the thumbnail.
Brand new saves (never uploaded before) all failed to upload. If you have a local copy of your save, delete the server version and re-upload it.
The server ran out of space due to a short attack on the servers. I noticed the attack at the time, but since the servers were still running, I didn't realize that the drive had also run out of space.