This might not be what you are looking for but it worked somewhat for me since I only want the count of related features.
Go into the Configure pop-up menu. There you will have the option all the way at the bottom to "Show related data" which will put a hyperlink in the popup that will open the attribute table of the related features. But also you can click the "Configure Attributes" link.
Then you should see the related table attributes but it only appears to allow you to display a count (which again is what I needed).