I apologize for it taking so long to get back to you! Our department has been mostly off for the past few days.
I've been digging in to this issue and I went through and replicated it myself. I can definitely see why you're frustrated! The issue is actually that even though the theme itself has been set to allow for a width of 1024 pixels, the container for posts is still set for only 800 pixels.
Clearly because it is going into an area which is wide enough, the container is able to stretch just fine, but our media uploader is reading the theme's width and stepping down the image width accordingly as it inserts the image.
I've reported this issue, but for now you will sadly need to either keep adjusting the width of the images or you might need to switch themes. Sorry about that!