Win10 – Unblock all files in a folder

Open a Powershell window (or a Command Windows and type Powershell).
CD to your folder path.
Run the following command :

dir | unblock-file

Or

get-childitem "C:\FolderPath" -recurse | unblock-file

It’s also useful to Unblock the ZIP file before extract, so all extracted files are unblocked by default.