Hello,
1. In order to add a new menu product category item, you should choose the category item from the “Product Categories” area that is situated from the left sidebar.
https://monosnap.com/file/aYAS5DhIttYw4od8Oej01ZpN2cjgyS
After adding a new menu item you will not see setups in it like on other items due to the fact that the menu was not resaved.
https://monosnap.com/file/UsmO7Sdmk8Gw02qab3flYhmlnMEkZG
Then fill in the fields as you need.
https://gyazo.com/ea96ff2d87546728ad791ac8ffa34e62
2. There is a bug in the Elementor plugin and you can read a similar issue on their Github https://github.com/elementor/elementor/issues/16467
As a workaround, you need to click on the “Preview” button while editing your footer HTML block. And always keep the preview window opened while customizing and saving your HTML blocks with Elementor.
Kind Regards