I am having the same issue with my Intel NUC based Roon ROCK server (with attached external USB drives for music file storage) after updating to the current update (Roon Version 2.0 (1212) early access) a well as at least the last 2-3 Roon Rock updates. It’s happened with all the updates lately where it will rescan my music library and add a couple dozen (or a couple hundred last time) albums as ‘new’, when they were already in my library. My post on that is here. I have not tried to restore the database though, like you have.
Hope it’s OK for me to reply in your support here – seems exactly the same problem, and I’d like to see what the fix is.