Yes, I have encountered the same problem. Had a page full of embedded tweets, all working fine…then last night all I had was copied url’s from twitter. I have redone the page, re-embedded the tweets to no avail. I was actually on 3.5 when the problem first surfaced and updated to 3.8 thinking that was the problem. No change. I was also using the twitter embed plugin at the time and have since deactivated, deleted, re-downloaded and activated again…no change. From what I’ve read, I shouldn’t even need the plug-in. Here’s the link to my site…
http://sdhorserace.com/favorite-tweets/
Could sure use some help here.
I am also having the same issue, and it just started today. I thought the twitter embedding was part of Jetpack so I sent them an email.
Hey guys – I found a ticket item addressing the issue – it seems to be a Twitter API problem. More information here: https://core.trac.wordpress.org/ticket/26844
Good spot Niki, Came here searching for the same problem, thanks for bringing it to our attention.