Hello,
Please see this conversation: Standalone Link for published Rmd Content - #3
The problem is that you are trying to embed an iframe within an iframe and our platform has security to block this. The hack would be to find the url in the iframe we use to load your app on Posit Connect Cloud.
Thankfully, this won't be an issue much longer. We will soon default deployments to an iframeless url that should make embedding via iframe work seamlessly.
I'll post an update here when that happens, likely within the next week or two.
Best,
Alex