Hi, I'm still newbie ;-) may be I made something wrong and it's not the first thread about it, sorry
once applied the following change, shared by @riteshpatelrtcamp (closed topic) https://rtcamp.com/support/topic/rtmedia-activity-updates-not-showing-in-activity-loop/#post-50996
<?php if ( bp_has_activities( bp_ajax_querystring( 'activity' ).'&action=activity_update,rtmedia_update' ) ) : ?>
For now... even if I set 'New Groups', 'Friendship' filter, etc, then all updates 're showed! (only updates, without any automatic updates like 'New Groups' for example)
PS: Not tried on a fresh install'.. it's on the road ;-) but in my case if I remove this modification, all is right
rtMedia 3.2.10 runing on WP 3.7.1 and BP 1.8.1 (twenty twelve child theme)