iFrames stopped working in Firefox which used to load earlier
We used to have certain pages with iFrames that worked fine in Firefox until last week.
However, the same pages are no longer loading as iframes.
Opaite Mbohovái (1)
If you are accessing the page in a private window, check for a Tracking Protection notification icon toward the left end of the address bar. This article has more info on this feature and how to make an exception: What happened to Tracking Protection?.
If that isn't the issue, try looking for an error message in the Browser Console. Press Ctrl+Shift+j to launch the console in a new window, then click the trash can icon at the top left to clear past messages. Switch over to your page and reload it, then switch back to the console and examine the messages. Ignore the blue triangle lines (CSS warnings) and look for script errors or security messages. Anything illuminating?