I’ve had this problem sooo many times! I grab a link from my blog and get ready to share it on Facebook, but the image won’t load and neither will excerpt. This happens every so often and it’s completely unpredictable, but I’ve found one thing that works…Facebook’s Linting Tool…now know as the “Object Debugger“.
If you head over to developers.facebook.com/tools/debug, you can add your link and click “Debug” to 1. Propagate your blog data into Facebook so that your preview will appear correctly and 2. View any errors in your blog data that may need to be repaired.
If you continue having issues with your Facebook post previews, one easy fix is to install a plugin (WordPress users) that will help you to propagate the correct data for every post, like Facebook Opengraph.