Yeah, preview doesn't accurately show what the post will look like. It should give a link to the image at least. (Preview also won't use the correct color for links.)
Does the same when leaving rich editor mode, then returning to rich editor mode. Just one of those things you deal with. However, I imagine if you replace the [ATTACH code stuff with clicking the Insert Image / Insert Thumbnail button, you should be able to see it again, hm?
