I am getting the same issue.
That feature worked, but does not work anymore in the version 11.0.
Indeed, if you choose: “Actions with multiple images” > “Set multiple images randomly as featured images.” > “Consider only posts without any featured image: Posts with featured images will be ignored, even if the Overwrite option is checked”.
Everything works fine until this stage, but when you cclick “Apply”, you get the error message “No matches found.”.
Hoping the author fix this soon.