Looking at your site I see it's now displaying the thumbnails. I'll drop the 2020 guys an email to see what the support status is with this plugin. I helped with the testing hence why I got listed on the authors, I only check on the messages myself every now and again for interest.
The thumbnails are rendered by a third party (rather than this plugin) so can take some time to be rendered. It's not something that the plugin has control over.
I notice you've got a problem on your site with another plugin too.
Fatal error: Call to a member function get_permalink() on a non-object in /home/swaldenb/public_html/wp-content/plugins/wp-latest-post-blogroll/wp-latest-post-blogroll.php on line 84
I'd suggest that there is an issue with one of the feeds, if you can work out which one then you might be able to fix the error without needing any code changes for that.
If you don't have any luck with that then you might want to try http://wordpress.org/extend/plugins/rssfeedchecker/ or http://wordpress.org/extend/plugins/feed-reading-blogroll/ which I believe do the same kind of thing.