Hello, @Paul Severn,
You need to use appropriate woocommerce and theme versions http://prntscr.com/gi5s1b so please update theme and woocommerce to latest versions
https://www.8theme.com/demo/docs/legenda/#!/installation_upgrade
Before uploading theme files delete “woocommerce” folder, which is located in wp-content/themes/legenda/ to avoid problems with old files.
Don’t forget to create backup of your files and database before starting update process!
You need to enter your purchase code to activate our new theme version and skip Setup Wizard.
Also, update all required plugins https://www.8theme.com/download-plugins/
Regards