Hi,
I believe I might know what the problem was. I see you have lots of shortcodes and lots of plugins using the content filter. So, what I did is that I have de-activated the following options on the related posts pro back-end: http://i.imgur.com/ndgnmq7.png
I have not done anything else, because I don’t want to modify anything on your site – so please let me know if this helped!