It appears that I have this same issue (only the admin and guests can see the forums). I tried adding this code to the functions.php file, but it doesn’t seem to fix it. I also noticed that I can create a new page and put the forum shortcode in it, and it the main forum page shows up for all users (which is what I need), but once I click on any of the forum links, it gives me a 404.
Any ideas, or maybe options I should change, or caches and whatnot that I should clear?
