They are working for my wife, but not for me as an admin or as a test user I set up. I've tested it on both my Mac and my PC.
The "Like" and "Share" buttons are provided by Facebook API. The "Tweet" button is provided by Twitter API. If you have any privacy protection add-ons installed to your browser such as Privacy Badger, Disconnect, Ad-block, or even just Firefox's Privacy Settings enable, than you wont be seeing anything from Facebook or Twitter. Those extensions also block third-party cookies and page elements which you have not specifically white-listed.
This not related to UBB.threads software, but instead related to your browser settings. In some cases, this could also be related to the settings on your DNS or within your router, if they are blocking social-networking sites. But you've said your wife has no problems seeing the Like/Share/Tweet buttons. If you're on the same network as her, its more likely to be a browser extension on your computer setup which is blocking them.
