A family of Microsoft word processing software products for creating web, email, and print documents.
I found the same issue with docx files recently. I'm glad I found this thread. Disabling background save works for me.
So it seems MS has STILL not fixed this issue. My version is Office 2016 (365 subscription). I find it hard to believe MS never knew about this issue. During their working days I'd imagine they use their own product and will surely notice this quirk relating to docx file saves. I know MS don't monitor the forum but it never ceases to amaze me how they can play dumb to issues. Do they not actually test their stuff thoroughly or use their software in everyday life (work and personal).