Codepen Repro: http://codepen.io/team/webflow/pen/QEKYax
In Chrome and Safari, the second Tweet button shows properly when the parent’s display: none CSS is removed:
However, in latest Firefox (47.0) and Edge the Tweet button remains hidden even after the parent container is displayed:
Looks like the corresponding iframe is set to be invisible https://cloudup.com/cCTGSH3CdIs (can’t post more than 2 images since I’m a new user).
Definitely seems like a bug on Twitter’s side since this works fine on Webkit/Blink browsers.