.ZIP from Windows to Mac: folder structure lost - how to avoid that?

I am creating .zip-files on windows that I want to make available to Mac-Users (created with ZipFile.CreatefromDirectory from .NET Core). However, when I extract these files on my Mac (running Mojave, using the context-menu's "Extract File"), it re-creates the source-folder that I had zipped - and a flattened structure in side that folder: where I previously had root\foo\bar.txt, I now have a file "foo\bar.txt" in the root-folder. How I can get a "foo" folder with "bar.txt"? Did that problem arise when I build the .zip or do I need to extract differently in order to preserve directory-structure?