The Featured image in a wordpress blog is to be displayed (the defoult) ONLY in posts and articles.
NOT must be comprehensive in all the blog pages because if you use as pulgin
buddypres
bbpres
the event calendar
etc. etc. etc.
This is a problem and all the blogs with wordpress plugin use.
The only solution I have now is to globally disable the featured image and activate the fatured image in every single article or page.
In my site I have more than 400 aritcoli! Activate the featured image for each item is something that takes a very long time!
I hope I made it clear.