Sorry, that’s frustrating! It would be helpful to know if this works with the latest bug fix release for your version (4.6.9), or newer. Archived previous versions are available here: https://www.plexim.com/download/blockset/archive
It’s possible there was an issue in your version that was since fixed. (For what it’s worth, I am successful with this using 4.6.9) Let me know!