I have searched all over the internet for an answer and although I can find a million people with the same question I cannot find an official solution to the problem im experiencing.
I always get "Cannot display preview. You can post as is, or try another link." displayed.
I've stripped a page down to only the required open graph meta tags so I know they work (run through multiple OG validators), Ive disabled any kind of robots blocking, any kind of redirects, disabled the firewall on a test server, made sure the LinkedIn bot requests are hitting the server. All I see in the browser console all the time is a status 500 being returned from LinkedIn's preview generator API.
We are hosting on Windows Server in IIS 8.5, it seems if I create a demo and host it somewhere else it works, which makes me think it is server related or IIS settings.
Reading this Linkedin post's picture doesn't appear in summary its seems like a similar issue. We are not serving over SSL so nothing to do with that.
I have already asked this question on LinkedIn's forum but having no luck, so im hoping someone on here can help or someone from LinkedIn's tech team can help.
Thanks