hello, faced with such a problem. template jxtc hardcore demo.joomlaxtc.com/hardcore/index.php/framework-xm-template-framework-xm/item/240-skateboards in k2 does not work in additional fields (drop down, multiselect, radio button). Like on this demo-"color variations:". problem with k2? or a template? joomla and k2 are updated to the latest versions

This is a template issue.
It is possible that you did not setup your categories correctly.
The template's developer will able to assist you on this.