Facebook Share Featured Image & Image protection

I was having a problem with shared posts from my WP blog showing the featured image as a thumbnail on my Facebook page. Realized that maybe it had something to do with the site-wide direct image linking protection I have set up in my site’s .htaccess file with a rewrite. As soon as I disable that protection, the thumbnail shows on Facebook. So question is, is there a way to have the image thumbnails showing while not disabling image protection? Suppose I could disable that protection from my WP uploads folder, but I’d rather not. That my only option?