I'm Richard - CRO Expert at PageFly Landing Page Builder. Welcome to Shopify Community!
Regarding your concern, please give me the URL of the page so I can check further for you.
In the meantime, if you'd like to achieve similar results, you could refer to the apps Reconvert Upsell and Cross sell or Cross Sell & Cart Upsell, in which Cross Sell app is already integrated with PageFly that allows you to easily use with drag-and-drop system after configuring the options from Cross Sell, you can check this manual for more details.
Please leave a Like if you find my answer helpful.
Best of luck!