Hi Nicolas,
I was using Firefox 27.0.1 version on Debian 7. The plugin is working correctly now and I am wondering if it was some temporary issue. Either with my database to which the plugin was not able to connect, but again other posts and everything else on WP was working. Or may be it was issue with FB or Twitter at that time and they were not responding with data.
I personally feel that it is better to remove these options to like the company page from the plugin.
I have uploaded the image screenshot which I had taken then, not sure if it will of any help though. Please check this post, https://blog.viggy.in/?p=696
Thanks for a very good plugin.