Use of Tokens in Json File Path

I ended up here because I see the "Note: Can use Drupal token as well." on the JSON file path setting, but when I put a token in that value, I can't even save the view. I'm getting the error:

Exception: Local file not found. in Drupal\views_json_source\Plugin\views\query\ViewsJsonQuery->fetchFile() (line 235 of modules/contrib/views_json_source/src/Plugin/views/query/ViewsJsonQuery.php).

generated from:

  public function fetchFile($uri) {
    $parsed = parse_url($uri);
    // Check for local file.
    if (empty($parsed['host'])) {
      if (!file_exists(DRUPAL_ROOT . $uri)) {
        throw new \Exception('Local file not found.');
...

So I headed to public function execute, right above where fetchFile is called, I can see where the replacement was supposed to happen. The comment references [site:url], so that's the token I was testing with. The replacement is not succeeding.