Upsells products are not working

Hello

Up-sells are products that you recommend instead of the currently viewed product.

They are typically products that are more profitable or better quality or more expensive. Depending on your theme template, these products display on the single product page underneath the product’s description.

Up-sells (user defined) show on the product page.

Here is more information: https://docs.woocommerce.com/document/related-products-up-sells-and-cross-sells/

You cannot show up-sells product in a sidebar.

Best Regards