Looks like you're not doing anything wrong at all! And chrome isn't giving you a great error explanation.
I would suggest testing issues like this in both chrome and firefox at the very least.
The issue is with the embedded site's security settings. Specifically the X-Frame-Options header. This is used to prevent the site's content from being republished on another site.
In FF you'd be seeing an error like this:
"To protect your security, ics.unicornplatform.com will not allow Firefox to display the page if another site has embedded it. To see this page, you need to open it in a new window."
Looks like you're not doing anything wrong at all! And chrome isn't giving you a great error explanation.
I would suggest testing issues like this in both chrome and firefox at the very least.
The issue is with the embedded site's security settings. Specifically the X-Frame-Options header. This is used to prevent the site's content from being republished on another site.
In FF you'd be seeing an error like this:
"To protect your security, ics.unicornplatform.com will not allow Firefox to display the page if another site has embedded it. To see this page, you need to open it in a new window."
I would recommend connecting with HubSpot Technical Support, as Support is included in your subscription and they will be able to provide real-time assistance for this matter, where you are able to share screenshots and further information about each matter you mentioned here.
If you have any issues connecting with technical support please let us know!