To find out if the problem relates to XStore theme, to need to check how categories work with Storefront theme (Appearance > Themes > install and activate Storefront).
If the problem persists with our theme only, provide temporary wp-admin and FTP access in Private Content area https://prnt.sc/n2okla
If you have problems with the default WooCommerce options even when the default Storefront theme is enabled then you need to contact WooCommerce plugins support. We can help you only in case the problem appears only when our theme is enabled or with XStore theme options.
I have added the product to category and it appeared on the frontend. Seems problem was caused by the empty category.