A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
It's working on my US English Version 1801 (build 8911.2016 Click-to-Run). What appears to happen is there is now a Folders "tab" at the top. You can pin there. Note, this is only going to allow you to pin folders that contain recently opened files. If you want to have a folder show that isn't listed - just open a file from that folder and go back to the Open dialog menu. I just tested it and it works exactly as I've described.