Shopify doesn’t allow you to apply discount codes before the checkout page.

For example, when your customers add their payment info to PayPal and then go to checkout the discount is not transferred to the checkout. This is why our bundles do not work with 'Express checkout buttons' and we remove these buttons for the bundles.

if you create a product out of your bundle and set it to be created as a single product you have a Single-BAP.

In this case, there will be no discount code created for it. (The product will be on sale)

Read the following article to see how to create a bundle as a product and set it as a Single-BAP.

Here you can read about the difference between the two types of Bundle as Products.

Since we automatically remove the express checkout buttons for all bundle products, if you create a single-BAP, contact support and we will restore them.