[Plugin: WooTumblog] Problems with post formats and buddypress activity stream

I have a quite peculiar issue involving WooTumblog and the BuddyPress activity stream. I want posts with the ‘image’ post format to show up differently in the stream (different type & image included in the content). I’ve written a filter to do this, but for some reason it is not triggered when I use the Woo Tumblog dashboard widget – the posts do show up in the activity stream, but as normal posts. When I post via Posts > New post, my filter works just fine.

Any idea what could be behind this? Does the dashboard widget somehow take a “shortcut”?

Example filter:

function bpgg_filter_image_activity( $type, $activity ) {

    // check if the post format is image
    if ( get_post_format( $activity->secondary_item_id ) != 'image' ) {
        return $type;
    }

    // change the type to 'new_image_post'
    else {
        return 'new_image_post';
    }
}
add_filter( 'bp_activity_type_before_save', 'bpgg_filter_image_activity' );