Default author box showing below articles

I have published an article: https://nimb.ws/97WQ5H & its shows the default author box that is there in the Elements - Author box hook.

I have added a new user, he is also the admin, I have also added him as an author from right sidebar in the post (https://nimb.ws/5NpVc0) but his author box is not showing below the post.

How can I get his author box below articles?

I don't think editing "Elements - Author box hook" is the solution because when I have more than 1 author on the site, then this option will not work.

Pls suggest.

Thanks