If you are unable to see text in the Upsell window, such as the title or description of the Upsell offer, this can be due to your theme applying a color of white to the text in the Upsell window.
To resolve this issue, you can apply some CSS to the text elements that are not appearing. Please visit our Bold Upsell CSS Styling Guide for help with identifying classes in the Upsell window.
If you are not comfortable making these changes, please contact our Customer Success team.