Issue With Blog Archive Page

Have been using the great Pinboard theme for a couple of clients for a number of years but have recently encountered an issue. When blog articles are displayed on a category archive page they all overlap one on top of the other, rather than follow the grid. All the articles appear at point one and nowhere else. For an example please look here: Page

I am at a loss as to why this is happening but if you could please advise me that would be fantastic! Looking forward to hearing from you soon.

Pete

[ No bumping please. ]