BuddyPress.org

It’s probably something to do with your OneCommunity Themeforest theme.

I’m guessing that the theme author put bp_head() before wp_head(). Pass that tidbit to the theme author or adjust it yourself by moving bp_head() below wp_head() in header.php.

If you switch to another theme like Twenty Twelve or Twenty Thirteen, you should see that the Sitewide Activity feed is placed last.