I have several sites in a multi-site installation. The main site of the network is fans.email. Then I have sub-sites: email.fight.tv, and gulfbreeze.com.
When I write https://gulfbreeze.com in a post on Facebook, Facebook creates a preview for that site.
However, when I type https://email.fight.tv, I get a preview of fans.email, the main site of the network.
The only difference I can see is that email.fight.tv has Yoast installed and the OpenGraph metadata is enabled for it. I disabled the OpenGraph part, but this did not seem to solve the problem. However, I know that Facebook sometimes caches previews, so I'm not sure I solved the problem or not.