Wp eCommerce: Insufficient data or categories supplied.

Hi All,
i am trying the plugin in order to export my product in ebay seller format.
I am currently using the last version of WordPress and WP eCommerce.
I am reporting to you the following unclear behaviors:

– I noticed that if i click on “category” no category is displayed.

– If i try to generate the file i obtain the following error:

“Error: error in AJAX request. Insufficient data or categories supplied.”

In case you wonder the shop is at this link https://degustitaly.com/prodotti/ and it is not empty

Do you have any advice?

https://www.ads-software.com/plugins/purple-xmls-google-product-feed-for-woocommerce/