Why is only the main product added to the cart, and not the add-on? (Essential Upsell app)

With a Product Add-on, the add-on is added to the cart when the customer clicks the product page's Add to cart button. If only the main product is added, the add-on was usually not selected, or the add-on step did not run.

Check the following:

1. Offer type and placement. The funnel must be a Product Add-on offer, placed on the Product page, and published. The app embed must be turned on for the published theme.
2. Selection. Check whether Preselect products is turned on. If it is off, the customer must tick the add-on before clicking Add to cart. Test by ticking the add-on yourself.
3. Add to cart button. The app adds the add-on only when it detects the button the customer clicks. If your theme replaces, hides, or copies that button, the add-on may not run. Test with the theme's standard button.
4. Other apps. A product options app, such as one with required fields, can stop the add-on from being added. Temporarily turn that app off and test again. If the add-on is added when the other app is off, contact support with the name of that app.

If the add-on still does not appear after these checks, contact support with your theme name and a screenshot of the product page with the add-on selected.