According to the magmi documentation you add a "+" sign before the base image if you want to include it in the media gallery.
I have done this but for some reason when I upload my additional media images the base image does not show in the media gallery with the media images.
Please help I have never had this problem before and I am not sure how to correct it.
The Magmi documentation for this can be seen here http://sourceforge.net/apps/mediawiki/magmi/index.php?title=Image_attributes_processor
Also when I import the media images the base image no longer shows on the backend but the base image still shows as the main image on the frontend.
I am on magento 1.8.1.0 with the newest php patch