I just built some dummy albums and tried a few of those. I got cover art for some of them. Wrong cover art for at least one of them, but cover art for the ones I tried.
Not sure what might preventing that from happening on your system.
For what it's worth, I'm using that feature (get from internet) less and less now. Not because of any problems. But because I mostly want large high quality covers and I don't find them as often as I'd like with the automatic function.
So I made a JRiver link (at the top of the interface where it says AMG, AMazon, etc) that goes to Album Art Exchange. Album Art Exchange typically has large high quality art for 90% or so of the albums I look up. Here's the search URL I use in the link:
http:////www.albumartexchange.com//covers.php?q=Hexify([Album])
Maybe that will be of some use.
Brian.