I just notice that my forum posts listed in the search results are not displaying the number of posts correctly and the date of the last post. I did change the template slightly a month or so ago to display better on mobile phones.
The number of posts it displays for everything is just 5. For anonymous users who visit the forum (like Googlebot) the number of forum posts that display for each post is 10. I also have link rel="next" and rel="prev" set for my page navigation so Google should be able to follow everything and display the correct number of posts and date for the forum topic in the search results. This has been working fine for years.
I am pretty sure the tweaks I did to the template wasn't the cause. The breadcrumbs for the forum topic also display fine in the search results.
I know it takes a while for the number of forum posts to get updated with the correct number when new posts are added on the search result page so I don't want to start tweaking things yet as it will take forever to figure out.
For forums what schema and/or rich snippets do people use on forum topic pages (if any) to help Google figure out forum posts?