I know this may be off the topic, but any help is greatly appreciate! I have post the same problem on buddypress.org, but I know their support is sometimes quite unpredictable, and lately I have no support answer from them.
Even before the upgrade of wpmu 18.104.22.168, I was using 2.4.8a and buddypress 1.1.2, the problem is that site wide activity, and each member's activity, and rss feed for activity is completely broken. It's not working at all. I remember buddypress 1.1.0 has no problem of such. Is there a way to fix the activity?