I wrote earlier that user submissions were not coming through. After testing, the issue is larger: I created a new Link Library and put the shortcodes on a new page -- "Display link submission form" doesn't show up at all, so something deeper is wrong with the link submission form. I uninstalled and reinstalled LL; deactivated all other plugins and that didn't fix it; and I installed LL on another WP site of mine and no problems. So if the problem isn't fixed by a reinstall or deactivating all other plugins, I have to wonder if there's some problem in my database.
Any suggestions on figuring this one out? User submission has been down on my site for some time and I need to solve this asap. Thanks again.