The problem I had was somehow related to Adblock. With Adblock running in Firefox and the filters EasyList, EasyPrivacy, and Fanboy's Social Blocking active the "Link or HTML" section failed to display. All I was seeing was the "Image" section when I opened the share menu.

The problem I had was related to Adblock. With Adblock running in Firefox and the filters EasyList, EasyPrivacy, and Fanboy's Social Blocking active the "Link or HTML" section failed to display. All I was seeing was the "Image" section when I opened the share menu.