The ajaxurl variable has been changed (https://bpdevel.wordpress.com/2012/05/01/ajax-changes-in-buddypress-1-6/)
Here is a quick fix.
in bpModLoader.php:
change (line 62)
if (is_admin()) {
to
if ( is_admin() && !$_REQUEST['bpmod-fe'] ) {
add (after line 89)
if ( $mainclass == 'bpModActions' ) {
add_action('wp_ajax_ajax-flag', array(&$bpMod, 'ajax_flag'));
add_action('wp_ajax_ajax-unflag', array(&$bpMod, 'ajax_unflag'));
}
in bpModFrontend.php:
change (line 144)
$get_data = array(
'bpmod-action' => $action,
'type' => $type,
'id' => $id,
'id2' => $id2,
'_wpnonce' => $nonce
);
to
$get_data = array(
'bpmod-action' => $action,
'type' => $type,
'id' => $id,
'id2' => $id2,
'_wpnonce' => $nonce,
'action' => 'ajax-'.$action,
'bpmod-fe' => 1
);
That should do the trick.
Cheers