Facebook link image disappeared

I have been posting blogpost links to Facebook for years with no problems.
The other day, I installed a plugin called crop-thumbnails, didn’t use it and uninstalled and deleted it. Since that day, my featured images don’t show up when I post links to Facebook.
I have tried everything, I even tried installing a plugin that would add the open graph meta tags and still the images don’t show up.

I’ve tried creating a number of posts since I deleted the plugin and none of them will show the featured image on Facebook. I have tried to debug the links here:
https://developers.facebook.com/tools/debug
The og:image doesn’t even show up. As if it doesn’t exist.

Any help would be greatly appreciated, I need to post my stuff on Facebook!