We have been developing a SharePoint 2016 on-premise which we deployed quite a few times to work through some bugs and issues. Every time you publish a new version you need to delete the App from the sites and re-add it to the page where you want to use it.
We found that every morning the app disappeared from the page where it was added. We could see the app under Site Contents but could not add it to the page again.
Turns out that when SharePoint cleans the recycle bin (of the older versions of the app) it removes the latest version as well, leaving a “shell” of the app.
To prevent you must remove it from the Recycle Bin after deleting it and only then add the new app.
Strange but true!