However, instead of "Current Post", i'm trying to select "Other Post" and then choosing the post I want to pull information from so that we can insert a custom/curated "related" post instead of using category or tags to related posts.
Whenever I pick the post/page, the field remains blank instead. See video screencast hidden link
That doesn't look right. I suspect there may be an error shown or some revealing details in the network request reply in the browser console.
Would it be possible to get access to your staging site to take a look?
Let me mark your next reply as private so that we can get log-in credentials from you—you may want to create a temporary admin user for us to use that you can later delete. And be sure to have a current backup of your site.
Can you also confirm the url of where we can see the problem.