Comments & reply's only showing on some posts

I have a 2 posts each with 2 comments (one user submitted and one reply by me). I can see the comments in the dashboard and also on the live website. I have approved all comments.

I can see the replies in the dashboard, but one of the reply’s is not visible on the post on the live website.

Can anyone suggest why some of the reply’s that I have wrote, are not being shown on the live site?

The more confusing part is, I have a little comment counter beside each post in the loop on the main page, and the comment counter for both is 2, meaning I have replied to each post.

the site is https://goo.gl/Cji7YE