This is a very common problem that keeps happening every now and then and specially if you are newbie then the chances are that you will be really irritated about it.
Actually, this is not such a hard thing to fix but if do not know much about wordpress or do not know much development work then in beginning you will really need to do some search on google or play with your wordpress to figure out the issue.
Well, as you are here so i would not leave scratching your head. I have solution for this and i myself just figured it out.
So if your wordpress posts do not show images when posted on facebook or any other social media then you certainly have not installed a plugin which is must to load your posts on facebook.
The name of the plugin is “Yoast Seo” yes you read that right. But simply installing would not solve the problem. You will actually need to make a little change in plugin settings which will then enable your posts to debug the images when posted on facebook.
Go in the yoast seo plugin dashboard and click where it says first time configuration. Click on that and it will take you to a setup page.
Simple provide the information its asking. Click next, you will see an option where it will ask you to hide your media or not, there you would need to select do not hide.
This was the missing setting which was blocking facebook to debug the post images. I hope i was able to offer some help. If you liked my post then please share it.