Products not showing after upgrade

A client of mine had a severely outdated version of this plugin. As I updated WordPress from 1.3 I also updated the plugin – not sure about the version, but at least five years old.

Anyway, the migration has worked and plugin has updated BUT, the products are not showing on the products-page using the shortcode.

Can anyone point me in the right direction for fixing this?

Oh, and I did delete all the theme files from my wordpress theme and copied them over again using the settings page.

I need help urgently.

https://www.ads-software.com/plugins/wp-e-commerce/