This is typically found when pulling a form into a web page through an Iframe. Check the page's HTML to see if the form is loaded through an Iframe element, as Paypal does not support loading within an Iframe. This is a conscious limitation imposed by Paypal for security reasons. If Paypal is an essential payment option seek alternative HTML containers, such as a div.

Please note, while we can help to identify why the Paypal page is not loading, implementing a fix may fall under custom HTML support, which would most likely be a billable service.

If this does not appear to be the case with your form Chat with Support and reference this article.