https://www.theregister.co.uk/2018/10/25/windows_10_zip_fix_nov/

Microsoft has confirmed that, yes, that whole zip-file thing is indeed a bug and, er, no. It won’t be fixing it until November. But hey, how about a new Windows Search?

A post by Microsoft on the software giant’s answers forum detailed the issue, which sees the OS silently skip files already in the destination while extracting from a zip archive. The problem only affects extraction using Windows’ own File Explorer.