Get count of custom post tags

why don’t you try:

function tag_count( $tagatts ) {

  $tagatts = get_terms( 
    array(
        'taxonomy' => 'gd_place_tags',
        'hide_empty' => false,
    )
  );

  $tagatts_count = count ( $tagatts );
  return $tagatts_count;
}
add_shortcode( 'tag_count', 'tag_count' );

it should actually return the term count. I’m just using php for Count instead of a wordpress function.