Hi,
Please save the badge once without entering anything in the discount field.
So that you're sure you don't have anything saved for it in the database.
Also, not that the badge will only display for products in the category "product category" or its sub categories, and only if the quantity fo the product is equal to 10 based on how you configured your badge.
So please make sure that your products match these requirements.
In the discount field, you need to enter the code of a discount you already created in the menu Orders>Discounts and select it in the dropdown which will appear below. If you enter something which doesn't match with a discount code, it won't take into account your text.