You are using the BP Nouveau templates, correct? Span tag works fine in the Legacy templates.
In Nouveau, all links are stripped of span tags.
See the calls to function _bp_strip_spans_from_title and functions like bp_nouveau_get_nav_link_text in buddypress\bp-templates\bp-nouveau\includes\template-tags.php.
So remove your span tag from the create subnav item function.
Instead, in Nouveau, use 2 filters for adding a count item.
So something like:
function masta_add_namings_count( $count, $nav_item, $displayed_nav ) {
if ( $displayed_nav == 'groups' ) {
if ( $nav_item->slug == 'namings' ) {
$count = true;
}
}
return $count;
}
add_filter( 'bp_nouveau_nav_has_count', 'masta_add_namings_count', 99, 3 );
function masta_add_namings_count_int( $count, $nav_item, $displayed_nav ) {
if ( $displayed_nav == 'groups' ) {
if ( $nav_item->slug == 'namings' ) {
$group_id = bp_get_current_group_id();
$count = 666; // pass the group_id to a function that returns the proper count
}
}
return $count;
}
add_filter( 'bp_nouveau_get_nav_count', 'masta_add_namings_count_int', 99, 3 );