We are running into an issue with Pretty Plugins on our multisite. Whenever we have the Pretty Plugins plugin activated and then activated bbPress on a single site the end-user is not able to see the post types registered by bbPress: Forums, Topic, Replies. However these pages do appear if you visit them directly in the admin by visiting wp-admin/edit.php?post_type=forum, etc.
I've traced this down to the 'show_ui' parameter in the regisister_post_types function of bbPress. Whenever I change that line to pass in 'true' it will always show the post type menus. So to me it appears as if something is messing with the capabilities and causing current_user_can( 'bbp_forums_admin' ), current_user_can( 'bbp_topics_admin' ), and current_user_can( 'bbp_replies_admin' ) to return false.
Any help with this is greatly appreciated.