Are you using root profiles?
Your problem may be related to a change which went live in 1.9.2. Have a read this ticket from comment 10 onwards:
https://buddypress.trac.wordpress.org/ticket/5307
You’re a legend, thanks for pointing me in that direction. As a result I have worked out a fix… 🙂
Hello I BuddyPress is gone now I only have 2 blank pages in the network and groups http://fanphone.altervista.org page “attività and groups”
PHP Fatal error: Call to undefined function bp_is_active()
That’s the error I get in my child theme functions.php