Hi @mdsmith1
Thanks for posting about this! I'm so sorry to hear that this happened 
Do you still have the blank version of Invoice02? I'm not sure why that happened, as I haven't found any similar reports of this issue yet, but I'm happy to take a look.
Also, were other apps affected or just this one? What was the last date available in the previous releases section?
In general, Retool maintains a history of app saves, but here are some actions I'd recommend if you see a blank app unexpectedly:
1). Check to see if Retool is experiencing an outage
2). Check the browser console for errors
3) Step back in the recent history of your app to see if a past page save is working better. Stepping through the page saves is helpful because they save automatically & happen much more often than the releases you may have manually created in the release management feature.
To use this history feature, append ?_historyOffset=5 (you can choose any number, but I'm using 5 as an example) to the end of your app url. This will allow you to "travel back in time" 5 steps. You can increase the number to go further back in time if you still don't see what you're looking for. The idea here is to go back to the most recent working version (lowest # possible) so you don't have to redo as much work (going back 1000 steps would likely show data, but it could be many, many changes behind). ***WARNING!*** If you make any changes to the canvas when traveling back in time, that past version will become your present version and it messes with the history, so be careful not to touch anything! Once you find a version that isn't crashing and you'd like to make that your present version, then you can make an edit to the canvas (move a component, add a component, etc) to persist that view.
As an aside, Enterprise teams that need more extensive functionality beyond our release management feature, should consider using source control to manage their apps.