Facebook has an Open Graph debugging tool where you can enter a URL and view a report of it’s findings. Try it with your Posts, Pages, archive pages, author pages, search results, etc. to see how NGFB presents your content. If there are Open Graph warnings, read them carefully — usually they explain that the information Facebook already has for this webpage is in conflict with the Open Graph information now being presented. This might be just the published and modified times, or (if the webpage has already been liked or shared) the title and image Facebook has saved previously.
When editing a published Post or Page, a direct link to the Facebook Debugger is also available in the NGFB Custom Settings metabox, under the Validation Tools tab.