Update to Wordpress 3.4.1 broke MarketPress Categories Menu

The Market Press Categories menu was working fine until I upgraded Wordpress yesterday to 3.4.1 but now it shows all the products in the page results whichever category is selected.

The breadcrumb trail identifies the Category correctly. The Category URL shows as ?product_category=42 etc.

Theme is Catalyst - Dynamik. All plugins and theme up to date.

I've disabled Catalyst SEO and deactivated the Floating Social plugin that was installed yesterday in case it was that, but to no avail.

If I create a custom menu using the MarketPress Categories then the Product page's html seems to run together in one block and there is no Next button in some, but not all, of the Categories.

All MarketPress settings are set to show 20 items per page but on the Category pages there is only one item.

Is there some way of fixing this by copying code over to the theme?