Disabled all the plugins except Xstore core, woocommerce and Elementor,
removed all custom css and php functions, cleared all the caches on the server and browser cache. still the same.
Cart icon seems changing when product added but emptied when you go to cart page.

Neither add to cart button on the product page nor the add to cart button appeared on the footer when scroll down work (clicking this second button also covers the modal window appeared on the right side)