Hello,
To reproduce:

1- load this page https://rosannadelariva.com/en/pedido-rapido/

2- Click at any “add to cart” button.

3- You will see that the sidebar widget is not opened. Take a look: https://drive.google.com/file/d/1-aGU3INjMOPHhHSM1-ugoNGo_2pnecfO/view?usp=sharing

The plugin that shows the product list is this: https://yithemes.com/es/themes/plugins/yith-easy-order-page-for-woocommerce/