SharePoint form customized with Power Apps not displaying

We have a SharePoint list with a form that was customized using Power Apps a few years ago. Recently, I was informed that the form is not loading. I don't know how long it has been broken, or if it started after a change to anything in the environment. I'm able to replicate the issue using Chrome and Edge. In Edge, it displays a blank screen, in Chrome, it shows "apps.powerapps.com refused to connect". In the browser Dev tools I am seeing the following error:

Refused to frame 'https://apps.powerapps.com/' because an ancestor violates the following Content Security Policy directive: "frame-ancestors 'self' https://*.powerapps.com".

We've made some adjustments to the CSP settings in Power Platform Admin for the Default environment, but have not been able to resolve this yet. The current setup we are trying today is in the image below. I was hoping that by removing all of the sources, we might be able to get it to work, but no luck thus far.

Previously, we had some domains entered in Source, like 'self', and *.powerapps.com, and even added some other ones yesterday. It doesn't seem to change the exact text of the error I'm seeing in the browser dev tools, which makes me wonder if there's a long timeframe between those changes and when they are fully in effect, or maybe I'm going down the wrong path entirely. If anyone has some additional troubleshooting guidance, I would greatly appreciate it. 

Thanks!

Brian