That's exactly it. It was one of those unintended consequences of blocking everything that led me down the road of figuring it out. Like other commenters have

That's exactly it. It was one of those unintended consequences of blocking everything that led me down the road of figuring it out. Like other commenters have indicated, I will likely need to go back and allow some other social media to access the OPG data for previews to render properly. But since I mostly post on LinkedIn and HN, I don't feel the need to go and allow all of the other media at the moment. That might change in the future.