Social Marketing Ads Not Showing on Blog Index

What might keep the Social Marketing shortcode from rendering ads on the index/home page of a blog when they display fine on the Single post page? See links below for example...

Here the ad displays fine:
http://gifts.tripawds.com/2012/04/13/save-on-tripawds-mothers-day-jewelry-gifts/

But no ad shows in that same post here:
http://gifts.tripawds.com/

Am I missing a setting somewhere? I don't think it is theme related because it's also happening here...

See ad in this post:
http://agreda.com/blog/2012/04/03/how-to-increase-viral-product-sales/

See no ad in second post
http://agreda.com/blog/

Anyone else experiencing this behavior? I'm hoping the awesome support staff here can try to replicate this issue and help provide a fix. Thanks!