I feel like this should be an easy question. According to the Apple Support site, and everything else I have read, when I'm inside a shared album and I click the people icon, I should see who has access to this album, and be able to add more people to it. This is actually what I see. No option anywhere in the UX to actually add or subtract people. On the iPad and iPhone, I can do it, but here on the Mac, WHERE I CREATED THE ALBUM, no people. I'm out of ideas.