Hello,
It looks the Recently viewed products appear for the logged-in users only. And it happens not just with our theme but with the default Storefront too. You can enable the Storefront theme, add the default WooCommerce Recently viewed products widget to the sidebar https://prnt.sc/1wm8d4q and test. So, contact WooCommerce support about this issue https://wordpress.org/support/plugin/woocommerce/ we can do nothing with this.
Regards