And it was such an easy fix!
Apparently the problem of work in progress being moved to an older, unused blog only happens when the work is being done in the Chrome browser, on a Chromebook. When I work in the WordPress app on my Android phone, or that app on my Chromebook, there is no such problem.
And when I work on this new blog in a Firefox browser on my Linux laptop everything happens as it should.
Wish all my problems could be fixed so easily! 🙂