iframe not showing is edit mode

Site URL: https://www.whobuiltme.com/built-database

Hi, I'm trying to embed a PowerBI report into my Squarespace site with an iframe code. When I do, I see nothing show up in the space in the editing mode on Squarespace, but when I open an incognito window in chrome and navigate to the page, I can see the report just fine. Is there a reason it isn't showing up in the Squarespace editing mode? And is there a way to fix that so I can make edit while being able to see my page as external visitors do? Thanks!