Possible Cause #1 – The Free version of the plugin is still installed and activated.
You can quickly check this by going to your WordPress Dashboard – Plugins and if you see this: instead of this: then you are still using the Free version which does not display images. Instructions and guidance to setup can be found here.
Possible Cause #2 – The plugin’s setting has been set to not show “media”.
Possible Cause #3 – The feed’s shortcode has been set to exclude=”media”.
Possible Cause #4 – The image(s) are being shared from a restricted Facebook account.
Possible Cause #5 – The “Photon” feature of the JetPack plugin is installed.
You can learn more about that feature here. Deactivating that feature in the plugin may resolve the issue. Please follow the instructions provided on this page on how to deactivate Photon for a specific site page.
Possible Cause #6 – An add-on or extension you have installed in your web browser (often Firefox) is blocking the photos being loaded from Facebook.
Try checking to see whether you have any add-ons or extensions installed in your browser and, if so, try disabling them to see whether that solves the problem.
Possible Cause #7 – You are browsing using Firefox’s “Private Browsing” mode and have “Tracking Protection” enabled in the settings.
You would need to disable this as it blocks some Facebook images.