Open Graph tags missing

Hi, I’m trying to figure out why OG tags are missing on my Tracks website. It is possible that it’s caused by a plugin, but vanilla Tracks doesn’t seem to generate them properly on my website, unless I install a 3rd party OG plugin. The OG:Image is missing completely for the main page and OG:Description uses the excerpt from the most recent post.

It works fine for posts on the page, but the homepage URL shared on Facebook doesn’t have any thumbnail. It is working now through a plugin I’m using.

Is this normal, or just something messed up on my server?

The page I need help with: [log in to see the link]