We are aware of an issue with Embeds in iFrames failing. This commonly manifests as a blank screen. When looking at resource requests you may see a 403 error or a log stating "Failed to load resource: the server responded with a status of 403 (Forbidden)".
This is due to missing information in the referrer header. Thanks for bearing with us as we work towards a solution. This page will be updated with any progress and new information.