I have installed Forums in a multi-site installation and activated it on two of the sites to test. One site uses my preferred Theme called "Standard" and the other uses Twenty-Twelve so I have a baseline for testing.
Both sites will not redisplay the topics page, all I get is "No topics to display...Click here to create a new topic." This is after I have added one or more topics and have added additional posts to the topic.
Also, on the "Standard" themed site I always get duplicate entries for the same topic along with the above behavior. Any ideas on what is causing this to occur?
I can give you a user login to see the behavior if you wish.