Why did the Twitter Widgets stop working?


I have several Twitter Widgets that have been working great since they came out some months ago. They are still listed in my https://twitter.com/settings/widgets page. In my website, the code has stopped working and just displays a link to the Twitter account’s timeline.
I checked the settings for each one: the settings are there and the embed code is there but the preview is not showing.

Is this a temporary glitch or have the Twitter Widgets been disabled?