Whenever the Autoptimize plugin is activated it fails the Mobile-Friendly Test. After going through a trial and error process to see if any one of the HTML, JavaScript or CSS options were causing the failure, I discovered it was the CSS option. I left it uncheck which now passes the Mobile-Friendly Test.
Will there be an upgrade in the near future for the Autoptimize so when the CSS Option is checked it will past the Mobile-Friendly Test?