Im actually having the same issue, however ive not activated the right side though, mine is just the background issue
Ive just wrote an article and assigned it a new background of its own, however it wont show it and reverts to the default one set in the theme options page.
Article is here >> http://www.jamespictures.co.uk/beginners-guide-to-social-media-for-photography/
2 background images assigned >> http://jamespictures.co.uk/images/background_problem.jpg
im still using v1.7 of the theme as ive only just noticed there is an update, If I get time tomorrow I will update the theme, but I dont think this is the issue as its working on other pages just fine.
Background changes fine using the same method as above
http://www.jamespictures.co.uk/picture-gallery/
Its also extremely bizarre how this blog post changes the background just fine
http://www.jamespictures.co.uk/nikon-d7000-oil-on-sensor-problem/
I dont get it ;-)
I will do some more playing to see why its not changing the BG image