Hi,
I have added a line of CSS code to hide subcategories on the header on desktop (Blue Box in the picture).
Please check out your website.
Subcategories are hidden in the mobile mode by default.

In order to add categories and subcategories on mobile mode, you can build a category menu with categories and subcategories link, then you will have a menu for the categories and subcategories on shop and categories menu. please see the attachment.

For the links, it seems that there is an issue with it, I have reported this issue with our developers and we will fix it as soon as possible.

Best Regards.