We are running WordPress 4.7.3 and Sydney Pro theme 1.5.
We have a Blog page and currently it has 2 blog posts showing (Post A and Post B.) The one post has 12 comments and the other post has 16 comments. If we create a new blog post “C”, then only the comments from blog post “B” show, regardless of which post I am in.
In other words I can be in blog post “A” and the comment section says “12 comments for blog post B”. If I put the new blog post C back into draft mode, then the comments work correctly on Posts A & B.
The problem also gets fixed by switching from the Sydney Pro theme to the Twenty Seventeen theme but not Twenty Eleven.