The description was generated but the product still shows the old text

Generating and applying are two separate steps, so it is possible to have good generated text that has never been written to the product. The app tracks these independently, which is what allows "undo, then regenerate" to return your stored text without silently republishing it. Check whether the item is marked as applied; if it is not, apply it explicitly. Applying content that is already stored does not consume allowance, because the content itself has not changed.