We are using F-secure Computer Protection in our company. I was recently asked to block all social media apart from Twitter, Linkedin, and Facebook.
I ticked disallow for social networking category. After that I allowed the sites, Twitter and Linkedin worked fine. Facebook was no longer blocked but it was displayed without any CSS. The only way I can get the site to work is to allow all social networking.
There seem to be other websites with similar issues, this was not an issue before we migrated from F-Secure Workstation.