Product sort not working on page load

We have had this issue on and off for over a year now and it’s definitely not helping conversion flow.

On loading a category page from a link the selected default sort option shows in the drop down but it only loads the products in order of newest first.

eg: You click Picture frames from the nav and it loads the category page with sub-categories at the top and products below. The sort drop down shows as ‘Sort by popularity’ as selected in the customize -> woocommerce menu. But the products are still sorted by newest first.

If you change the drop down to a different sort order it works perfectly, and if you change it back to ‘Sort by popularity’ it works and finally loads them in the correct order. It even stays working if you CTRL +F5.

It just doesn’t work on first loading the page from the link.

Has anyone else excperienced this? I can find loads of threads regarding sort not working all together but none with this particular issue.

The page I need help with: [log in to see the link]