Looks like some Windows "experts" missed how to correctly store subdirectories inside zip files. So a file "file.txt" in a subdirectory "folder" becomes a file with a backslash inside the filename: "folder\file.txt"
This is easy to reproduce on Linux. Simple place a file with a backslash inside the filename into a zip.
echo test > folder\file.txt
7z a test.zip folder\file.txt
Sadly the Windows-Explorer extracts this as a file "file.txt" inside a directory "folder". (tested on Windows 7)
Especially this software tends to create XLSX files (which are basically zip files) with this bug.
Bio-Rad CFX Maestro 1.1 Version 4.1.2433.1219
7-Zip on Windows also extracts "folder" as a directory. And in some sense the behaviour may just be described as platform dependend, because on Linux a backslash can really be part of a filename. So in this sense it's not a bug.
Nevertheless, I wanted to ask if you might have an elegant solution for this.
correction (somehow backslashes got lost):
echo test > folder\\file.txt
7z a test.zip folder\\file.txt