addEcommerceItem - Product Category not defined

To keep it simple I attach screenshots. Please advise what I am doing wrong or why . Thank you!

Coding examples taken from Ecommerce Analytics User Guide - Analytics Platform - Matomo

1) Fire the ecom events:
image

2) ecom event visible at ecom log (but no category visible)
image

3) ecommerce -> products -> product category(no category avilable):