The ImportError is probably because you don’t have the Facebook service added, but you’ve got the Sign in with Facebook box checked in the Users service (just as in this thread). But of course you can’t add the Facebook service, seemingly because of a bug! If you didn’t want to use the Sign in with Facebook, you might be able to work around it by unchecking that box.
Clearly you’re also having issues with the saved version of your app not agreeing with the version you’re seeing in the Editor. Just to check the obvious thing: did you hit ‘publish’ in the save history? If you did, your published verison will differ from your development version.
These issues are both tricky to reproduce! If you’re happy to share a clone link to your app I might be able to see the problem for myself in the cloned version.
It would also be helpful if we could see the contents of your brower’s developer tools network tab while the suspected bad saves are happening. There might be HTTP requests made by the editor that are timing out.
(Moving to Bug Reports.)