Website only displaying latest posts when Crtl +F5 is used

Hi I don’t know is this is linked to this plugin but it does seem to be something weild with caching on my site.

When you navigate to my site by typing in the url https://www.geeksyndicate.co.uk it is showing the latest post as dated 26th April. This is not the case as we have posted several articles since that date. If you a CTRL + F5 the site refreshes and you see the new posts. The problem is when you type in the address again it loses the posts again.

I tried emptying all the caches but the problem remains

Any and all ideas welcome.