When I tried sharing a record on Facebook, while I was writing the post, it showed the cover, but looked like it was including information from the login panel. Then when it was posted, it didn't include the cover or the login info. It did include the record title, but the image was the catalog banner/logo. Something isn't quite right with the social media posting. At least with Facebook.
I am not sure if we could share the cover like this, as there is copyright on covers and service agreements might now allow sharing to third party websites. But I believe we did improve the information shared at some point, maybe you could try again?
Looks like there is some improvement since I reported the issue. Would be nice if admin had the option to include the library logo or something.
I think the proper fix for this kind of issue is Bug 9855. *** This bug has been marked as a duplicate of bug 9855 ***