We switched to sorting by rating, but this has the effect of removing many FAQs from our home page. Some FAQs had a postmeta 'votes_count' of 0, but many of the FAQs didn't have a postmeta for 'votes_count' at all. These entries were not created by the q-and-a plugin for all FAQs when I enabled ratings (as they should have been by the plugin).
So, if you find yourself in this situation, you can run this SQL query to ensure that all records without a 'votes_count' postmeta value show up on your home page.
insert into wp_postmeta (post_id,meta_key,meta_value) select p.ID, 'votes_count',0 from wp_posts p where post_type = 'qa_faqs' and p.ID not in (select p2.ID from wp_posts p2 left outer join wp_postmeta m2 on m2.post_id = p2.ID where m2.meta_key = 'votes_count');