Are you using bleeding edge image formats and having issues? This may be the problem.
I was monitoring posts in the Joomla FB group when I came across this issue that in fact isn't just Joomla specific at all.
If you are using WEBP or other image formats they may not be showing up for you because the FB spec is GIF, JPG, or PNG only for OG images.
Here is the FB link for all the deets on this issue (further down the page under Images or all the things. https://developers.facebook.com/docs/sharing/webmasters
NB: Sorry about the contrast that is FB and using light green for part of the text is an accessibility horror show.