@girish not sure about 0 size ever, but I don't think so.
Anyway, after deleting some new .bak files from /app/data/data, Cloudron System Info now reporting a more reasonable 455Mb size for the deployed app.
Will try and keep an eye on it.
May export, uninstall, reinstall, import.
Although I think I did that once before.
Clearing all stats and shrinking database gives a 1.5Mb size.