non blocking minify settings

Hi, I want to use these rules https://developers.google.com/speed/docs/insights/BlockingJS

under minyf settings I set all scripts in head and body/after body to:
non-blocking using whatever (tried them all)

then empty cache, look at source code, but there is no such attribute like async added to my scripts: <script async src=”my.js”>
Did I miss a setting?

Any help would be appreciated

https://wordpress.org/plugins/w3-total-cache/