This is an intermittent error that a few people have been experiencing. We are trying to track down the source of this error and will have it fixed as soon as we can. One thing that may help is to refresh the page which will trigger it to sync everything.
It is ok to leave the page with unsaved changes as long as you come back to the page to sync those changes at some point. The outline section was designed to be robust and to work when the internet connection goes out, or if the server is unavailable. It will keep working and will sync up changes that you made while offline whenever it has a chance to connect again.