This is not a known issue. Or any limitation that I've heard of.
I made a simple list view with a few records, and a container with an image. The first two records I used "insert picture", the last "insert file". WebDirect shows the popovers containing the first two images as previews, and the last as a file, just fine in list view. Screenshots attached.
You have not listed your server details, or the details of your container configuration. That may have something to do with it. Also, the position of the popover may have something to do with it as well.
Thanks for the quick reply, Mike.
I did some experimenting after reading your reply and found that it doesn't seem to be keyed on the position of the popover button on the layout but rather the height of the row. If it's too narrow, the popover won't pop. i beefed up the height a bit and was able to bring things back to life. Shrink up your row height and see if you can replicate this in your db. I'm curious if you see the same thing if it's made pretty narrow.
I resized my row height to 25pt. Made the popover button 25x25pt. Works fine.
I'd imagine you are overlapping your object outside of the body part. If that's true, then that IS a no-no for webdirect development. I always use the position tab in the inspector to make sure that my object coordinates line up in the boundaries of the layout part it's placed in.