Question
How to filter and display only products on sale
Answer
ATTENTION! Before we get started, please keep in mind that the routine described below works only with Simple WooCommerce products. To see the product details, go to Products > All Products, then click to “Edit” any, and scroll down to the Product data section. If chosen any but “Simple” Product type, the Radio filter might not work as expected.

If you happen to run a WooCommerce store and fail to display all the products on sale at once, there’s a solution. You can create a dedicated JetSmartFilters Radio filter that will work out perfectly. It will give your visitors and users the possibility to apply just one filter and see all the products, which are currently on sale.
Create a new Radio filter and configure it as shown below.
Go to SmartFilters > Add New and setup the Radio filter as follows:

In the Query Settings section, make such to input the following settings:

Press the “Publish” button.
Add the newly-created Radio filter to the page.
Go to the product catalog page and open it in Elementor. Find the Radio Filter widget and place it anywhere you consider necessary. In the Select filter row, find and pick the filter you’ve created at Step 1. In the This filter for drop-down, select the archive page you are willing to apply this filter to.

Press the “Update” button and proceed to the frontend.
Check out the frontend result.
Tick the Radio filter and enjoy the result!