When I use my site’s home URL (http://www.sgbizconsult.com/) on Facebook, the thumbnail is a photo that isn’t in my media library. I tried setting a featured image for the page, but that didn’t fix the issue. I tried using the Facebook Thumb fixer plug-in, but it messed with my pages (I use Sydney and SiteOrigin), so I deactivated it. Any suggestions how to find and delete the images that must be coming from the default Sydney theme? I’ve seen related threads, but they require changing php code and I’d rather not do that.
Try to use the “WP Facebook Open Graph protocol” plugin.
Let me know how it goes.