BuddyPress.org

Hah! I finally found what was wrong!

It’s not possible to use a secondary blog as the “material/theme” for Buddypress. At least not for the forums. It has to be the primary blog (that has incorporated BP).

Changing which blog that is this on bb-config.php doesn’t help.

$bb->wordpress_mu_primary_blog_id = 2;

Well, now I at least know why I had my problems.