WARNING: App availability depends on referenced model existing
Yesterday, I refreshed our Dev and Test models from Prod to start a new development cycle. The Dev and Test models were actually brand new (only about a week old -- no in-model development, only App development) and didn't think I had any actual need to keep the previous versions since I was just looking to refresh data.
I had been working on an App that pointed to the Dev and Test models that were deleted. I wrongly assumed that I would be able to simply remap the app to the new versions of the models. However, deleting of the model actually deleted the app. Wow.
A similar concept applies to archiving -- although this does not delete the App, it does hide it until the archived model is restored. Only then can you point the app to a different model and re-archive.
This concept needs WAY MORE ATTENTION. I am hoping that Anaplan Support will be able to restore the workspace in question from 24 hours ago, as this would not harm anything and hopefully would restore the app. I will update this post when I get more info... Wish me luck.
Please see the following links for more information and upvote!!! This really was a bad surprise that I didn't expect, based on the fact that an app can exist without any pages.