Embedding youtube/twitter/instagram

Embedding is not working for me. Is there some setting I have to turn on? I swear at one point I think it was working. Also when I add a twitter link it gives me this error “Sorry, we were unable to generate a preview for this web page, because the following oEmbed / OpenGraph tags could not be found”. I am pretty new to this. Appreciate any help.

Have you set up Twitter on your instance?

For example, I put in the embed code and nothing shows up in preview.

You can’t use html embed code.

Try pasting the link on a new line by itself.

For example