I updated and made changes yesterday to my app and now when I log in the app is showing up as a previous version and all my changes and updates are lost!! I hit save and published the app yesterday after I made the changes!!
Have you checked the version history of the app? I've had problems with saving before (all thankfully just minor edits). It might not be saved after all.
Also, when PA accidentally closes, it offers to retrieve lost changes. When you do that, it doesn't open the app but rather makes a duplicate of it. So, when you hit save, it prompts you to save it at a desktop location. The online app doesn't get updated AFAIK. That might have been your case.