Social bookmarking on different browsers

I’ve noticed inconsistent behavior with the Social Bookmarking plugin on different browsers. For example on Chrome I see the icons while on Firefox I see nothing under the social bookmarking header (see attached screenshot for Firefox behavior). I’ve made sure I have no browser extensions/addons on while testing this in both browsers. Is this something I can fix?

Thank you!

Firefox:

Your browser is probably just blocking them. Firefox has some built in “tracking protection” blocking.

I can confirm I had a similar problem with Opera, and found out that the m.addthis.com tracker was blocked; by simply disabling tracker blocking for the repository, all Social Bookmarking icons were back again.
Hope this helps.