When I try to share a "discussion" (which is merely a link from our website) at linkedin through the "Attach a link", it used to pull a nice image earlier, but it ceased to do so now.
Is there a meta property="og: we should specifically use for linkedin shares to have an image shown?
Add these meta to your webpage head tag.
<meta property='og:title' content='title'/>
<meta property='og:image' content='image/path'/>
<meta property='og:description' content='description'/>
<meta property='og:url' content='your url'/>
While posting on the Linkedin, there is a linkedin cache so if you are going to re-post the same url again, probably the meta will not be picked up. To fix that you can add a parameter at the end of the url while posting on linkedin
e.g original url www.example.com then you can repost this with www.example.com?1