Check the href value declared by the comments box.
Look for class="fb-comments" in the page source to find the Comments Box XFBML. The data-href attribute should be unique to the page.
Niall, I appreciate your help!
This does indicate is a consistent page URL that is the issue – but you haven’t provided information about where in WP or the Plugin this reference value is set, or how to change it.
Any insights?
The Facebook plugin for WordPrses uses the get_permalink() to associate the Comment Box with the post URL.
To help others in the future, I identified the issue as an option in my theme – in this case Optimize Press – to choose the page that comments are tied to. This apparently sets the value for the Facebook plugin and over-rides the “real” permalink of the page. Choosing the same page you are working on corrects this issue.