Version 4.0 installed, no featured post thumbnails?

YARPP *should* choose the featured image of the related post, if available. By featured images, I mean this: https://en.support.wordpress.com/featured-images/#setting-a-featured-image

If you have featured images set for posts, but they’re not showing up, this would be a bug. Please let me know.

Hmm…now it is working fine! Perhaps it (YARRP) took some to build a database of images, or something like that?

YARPP doesn’t build any database of images, but it uses WordPress’ builtin post thumbnail service, and it’s possible that that took time to create the thumbnails of the right size.

Glad you got it working. ??