Help understand how products on my website are programmed.

My site has Gold, Silver, Bronze and Public member levels. Each gives access to different levelsof access view of blog content.

How is the site arranged to restrict Silver from "seeing" Gold member content? Same for Bronze restricted from seeing Silver member level content.

I think it has to do with addiing the product and tags. So, on the staging site (https://haejin.staging.wpmudev.host/), I added the Diamond Product with the appropriate tags and published it.

However, when I select new post; the "Access Allowed" section doesn't list the Diamond; only the Gold, Silver, Bronze and Public.

Can you help me understand why the Diamond level is not showing?