Why can't I see embedded social media posts?

Post date: 2018-01-10 15:25:21
Views: 5
A couple of weeks ago, I suddenly couldn't see Tweets embedded anywhere outside of Twitter. I can't see Instagram embeds or Facebook embeds.

I can't even see Facebook comments on sites that use them, like Buzzfeed. Come to think about it, I can't even see Buzzfeed's in-house comment system anymore. Everything looks fine when I go to Twitter or Facebook, just not on other sites. I still post embeds at more than one site, and no one has complained about not being able to see them. I just get a blank box for Instagram and plain text for Twitter embeds.

I Googled the question, and the results make it appear that no one has ever had this problem before. I use Firefox on a 2016 iMac running High Sierra. I've rebooted, repaired the disk, installed all updates. I do not use AdBlock. Anything else I can try?
From: http://ask.metafilter.com/317756/Why-cant-I-see-embedded-social-media-posts
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